Aerospace Telemetry (IRIG 106 PCM & CHAPTER 10 intro)

TELEMETRY is the process in which object characteristics are measured. These measurements result in transmitting these results to a faraway station where they are analyzed and displayed.

Telemetering information over wire had its origins in the 19th century. One of the first data-transmission circuits was developed in 1845 between the Russian Tsar's winter palace and army headquarters. In 1874, French engineers built a system of weather and snow-depth sensors on Mont Blanc that transmitted real-time information to Paris. In 1901 the American inventor C. Michalke patented the selsyn, a circuit for sending synchronized rotation information over a distance. In 1906 a set of seismic stations were built with telemetering to the Pulkovo Observatory in Russia. In 1912, Commonwealth Edison developed a system of telemetry to monitor electrical loads on its power grid. The Panama Canal (completed 1913-1914) used extensive telemetry systems to monitor locks and water levels.

Wireless telemetry made early appearances in the radiosonde, developed concurrently in 1930 by Robert Bureau in France and Pavel Mochanov in Russia. Mochanov's system modulated temperature and pressure measurements by converting them to the wireless Morse Code. The German V-2 rocket used a system of primitive multiplexed radio signals called "Messina" to report four rocket parameters, but it was so unreliable that Wernher von Braun once claimed it was more useful to watch the rocket through binoculars. In the US and the USSR, the Messina system was quickly replaced with better systems (in both cases, based on pulse-position modulation).

Early Soviet missile and space telemetry systems which were developed in the late 1940s used either pulse-position modulation (e.g., the Tral telemetry system developed by OKB-MEI) or pulse-duration modulation (e.g., the RTS-5 system developed by NII-885). In the United States, early work employed similar systems, but were later replaced by pulse-code modulation (PCM) (for example, in the Mars probe Mariner 4). Later Soviet interplanetary probes used redundant radio systems, transmitting telemetry by PCM on a decimeter band and PPM on a centimeter band.

Image 1: Space telemetry systems 

With telemetry, data can be transmitted via air, copper wires, or fiber cables.

If we want to use separate transmission channels for each measured quantity it soon becomes too expensive and very impractical. That's why telemetry groups measurements into one single format, that can be transmitted as a single data and in the end separated again into primary components in order to be analyzed properly.

Because of telemetry, we can monitor experiments from a safe distance.

Telemetry is used when standard wireless communication like WiFi data transmission can't be completed because of the larger distance between the antenna and the observed object. WiFi transmission gets limited really quickly, but with telemetry, more than 10 billion kilometers have been covered.

The complete telemetry system can be seen in image 2.

Image 2: Telemetry system 

As you can see, we distinguish between two sides when it comes to Telemetry:

• Airborne side (rocket, missile, aircraft).
• Ground side (ground station).

The airborne side can be Rocket, missile or an aircraft. Let's take a rocket to describe this example.

Image 3: Airborn block diagram shown on a rocket 

When we launch a rocket there are many things we need to measure for real-time flight control and for future performance developments. These measurements can be done with many different sensors (pressure, temperature, acceleration, etc.), aircraft bus communication (ARINC 429 & Mil-STD-1553), GPS position, Discrete data, Flight computer information, and many other things.

ARINC 429 is a data transfer standard for aircraft avionics. It uses a self-clocking, self-synchronizing data bus protocol (Tx and Rx are on separate ports). The physical connection wires are twisted pairs carrying balanced differential signaling.

MIL-STD-1553 is a military standard published by the United States Department of defense that defines the mechanical, electrical, and functional characteristics of a serial data bus. It was originally designed as an avionic data bus for use with military avionics, but has also become commonly used in spacecraft on-board data handling (OBDH) subsystems, both military and civil. It features multiple (commonly dual) redundant balanced line physical layers, a differential network interface, time-division multiplexing, half-duplex command/response protocol, and can handle up to 30 Remote Terminals - devices.

The role of the PCM Encoder is to measure all these signals in their own unique way. For all the analog channels that make up a majority of the telemetry data, the PCM Encoder has built-in signal conditioning which provides excitation to each individual analog sensor (just like our SIRIUS DAQ signal conditioning) and then measures the signal of each sensor. Behind the Signal Conditioning, the PCM Encoder has A/D converters to measure the input voltages from each sensor and converts it digital value. There are also special channels on the PCM Encoder for specifically measuring the other unique inputs the Flight Instrumentation Engineer needs to see from other digital data sources on the aircraft (Aircraft Bus Channels, GPS, and more).

After all of the channels are properly sampled the data moves to the Time Division Multiplexer (also referred to as TDM.) TDM pulls data from each sensor and creates the PCM Major Frame. The Major Frame can be divided up into Sub Frames or also called Minor Frames. Each Minor Frame is separated using a Frame Sync pattern (FS). Frame Sync pattern is a known bit pattern calculated to have a low probability of random occurrence. The Frame Sync pattern usually takes up 2-word locations for better performance.

Time-division multiplexing is a scheme in which multiple incoming digital signals are combined for transmission onto a single transmission line using interleaved time slots. Each incoming channel is allocated a specific time slot, and has full access to the transmission line during its allocated time slot. Some TDM systems allow for a variation in the number of signals being sent along the line, and will adjust the time interval of each slot to optimize the use of the available bandwidth.

Image 4: Time-division multiplexing 

Below is the standard frame sync pattern.

Image 5: Optimum frame synchronization patterns for PCM telemetry 

When viewing the Major Frame the Frame Sync patterns will be lined up. Traditionally a Sub Frame ID counter channel is added to the minor frame to know exactly which minor frame you are on in the Major frame.

Different signals acquire different sampling rates in order to keep proper channel resolution. Some signals need to be sampled more than once per minor frame (vibrations, position) and some of them less than once per minor frame (fuel level). There is a possibility to optimize our bit rate by sampling all the channels differently. These different types of sampling are referred to as parameter commutation.

Normal Commutation - signal is sampled once every minor frame

SFID stands for Sub Frame Identifier.

Image 6: Normal commutation samples the signal once on every minor frame 

Super Commutation - signal is sampled multiple times every minor frame

Image 7: Super commutation samples signal multiple times every minor frame 

Sub Commutation - signal is sampled less than once per minor frame

Image 8: Sub commutation samples signal less than once per minor frame 

Random Commutation - signal is sampled randomly throughout the major frame. Not on an even interval in a minor frame or subframes

Image 9: Random commutation samples randomly through the major frame 

Random Normal Commutation - signal is sampled randomly in a minor frame (not on an even interval) but sampled at the same word location for every minor frame in the major frame

Image 10: Random normal commutation samples randomly in a minor frame 

The best way to help visualize this Commutation is by using rotating gear. Signals have different sampling rates, so that means that they will be sampled at different times.

Image 11: Visualizing commutation by using a rotating gear

 

With Time division multiplexer (TDM) each channel gets sampled for an instant by the multiplexer. When the wheel rotates for the first time it samples the data from each sensor and writes it to the memory - puts it into the first minor frame. Then the sequence starts all over again. We need to make sure that it always makes a full lap. This lap needs to be done fast enough in order to keep the proper sampling rate. Sometimes some sensors need to be sampled at a lower rate than others. In this case, we use sub commutation and in our rotating gear example, we add a second inner rotating gear. When we have a parameter that needs to be sampled faster then we can use Super Commutation. This means we will sample it multiple times on our gear example.

Once our major frame is configured the data is passed along to the PCM Generator. The role of the PCM generator is to take each minor frame and line it up in a continuous data stream by separating each minor frame with a Frame Sync pattern. The Frame Sync pattern is used to show the separation of the data so the ground stations can rebuild each minor frame.

Image 12: Frame sync building diagram

 

Once the data is in a single row then the PCM code type can be selected. The PCM Code types shown below are ways to define the analog signal in comparison to a clocking signal. These are designed to allow other hardware to record the Analog data in a digital format.

Image 13: PCM code types and their definitions 

If interested you can find standards on a WSMR U.S. ARMY web page.

Next, the data is sent to the RF Transmitter to be sent to the antenna for transmission to the ground. The RF Transmitter will only put the analog data (dropping the Clocking signal) onto the RF Carrier. The Transmitter will run a low pass filter to smooth out the data signal that currently looks like a square wave. This filter will make our signal look more like a sine wave to allow better modulation of the data to the RF carrier. The RF modulation is done using different RF modulation schemes. The most common is Frequency Modulation (FM) in which the Frequency will slow down or speed up according to the analog data signal.

Frequency modulation (FM) is the encoding of information in a carrier wave by varying the instantaneous frequency of the wave.

Image 14: Binary frequency shift keying (BFSK) 

FM is only one of many modulation schemes used in the Telemetry fields. Other RF Modulation schemes include but not limited to BPSK, QPSK, and SOQPSK It is beyond the scope of this tutorial to go into detail on exactly how the RF Modulations works.

Once the data is on the RF carrier the RF signal can be sent to the antenna on the exterior of the rocket to be transmitted to the ground in real-time. The obstacles and challenges in dealing with the RF world are beyond the scope of this tutorial. Let's move onto the ground side.

Image 15: Ground block diagram

Ground Station Diagram

Image 16: Ground station diagram 

Currently our data is being transmitted from the Rocket on an RF signal. The job of the Ground Station is to recover this signal, clean up the signal, process it back to individual sensors on the rocket so flight engineers can see real-time what is going on during the flight.

At the front of our Ground Station, we have an Antenna that is looking directly at our Rocket as it flies. The antennas can range in size from 1 foot in diameter to a large 30 meter but the average telemetry tracking antenna is about 2-3 meters in diameter. Antennas can watch more than 15 different RF streams simultaneously. The antenna's role is to receive the RF signal from the Rocket and bring this down onto RF cables into the Ground Station.

The first piece of hardware that is in the Ground Station is the RF Receiver. This Receiver will bring in the raw RF signal from the antenna to be down-converted and demodulated to extract the raw data from the RF Carrier. The down-converter in the antenna slows the RF carrier down in frequency to get it to a manageable frequency. Once this is on the manageable frequency the demodulator will extract our raw data stream from the RF carrier. The output of the receiver will be a raw 'Video' stream that needs to be cleaned up.

This noisy signal is next sent to a Bit Synchroniser which can be built into a Receiver or an external piece of hardware. The role of the Bit Sync is to first lock onto the data signal that is hidden in the noise. Then it will clean up the signal so that it can then generate a Clock to match up to the data rate of the stream. This is extremely important to have the clock perfectly match up to the data rate. This data rate must be known by the Ground Station setup in order to lock up to the signal. The output of the Bit sync is 2 analog signals the data and the clock (CLK).

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Bit Sync Diagram

The first task of the Frame Synchroniser (Sync) is in hardware to digitise the Data and Clock signals back into binary/hexadecimal values. Frame Sync then in software will look at the data stream to find the known pattern of bits called the Frame Sync pattern. One the Frame Sync finds a frame sync pattern it then begins to count the total number of bits per minor frame it is told in its setup. Once the frame sync counts the exact number of bits per minor frame it should see the first bit of the next minor frame frame sync pattern. If the Frame Sync sees this it will be 'Locked' up to the minor frame.

Image 17: Bit sync Diagram 

If there is a Sub Frame ID (SFID) for multiple minor frames per major then the Frame sync can count that value to perfectly line up the Minor Frames per major frame. This allows the Frame to be perfectly lined up so that the parameters can be extracted correctly by the Decom.

Image 18: Frame sync building diagram 

The last step now is to go into the data and decommutate (also known as Decom) the individual data parameters. The Decom is done by Dewesoft X strictly in software.

Image 19: Decom is used for decommutation of the individual data parameters

 

This allows for the extraction of the complex parameters no matter what type or how they are configured in the Frame. In the Decom the user has to define exactly what the parameter name, units, scale, data type, and exact bit locations in the Major frame. This can be a tedious process to set when you have hundreds of parameters to set up. For these standards have been written like TMATs (Telemetry Attributes Transfer Standard (IRIG 106 Chapter 9)) which is a universal setup file so the Airborne side or other Ground Stations can be set up by one file type. The output of the Decom are time-stamped individual parameters for real-time display, transmission over Client/Server networks and/or Recorded for analysis.

The last thing to touch on the Ground Station is the data recorders. Since with a Rocket launch you only have one shot to get the data you have to make sure you have the data. So there are many different places that you can record data to make sure no matter what happens you can recover the data. This can in the RF world be done with an IF Recorder and then in 'base band' the Bit Sync and Frame Sync can be recorded with a recorder. The IRIG Standard recording format for the base band data is referred to Chapter 10 format per the IRIG Standard Chapter 10, which defines this (Not a creative name). This recording format allows for playback of the data file on any vendors Chapter 10 recorder or allows for data to be brought directly into software like Dewesoft X for processing.

Ground Block Diagram with Recording Options

Image 20: Ground block diagram with recording options 

Chapter 10 recorders have now added the real-time feature that they can record any type of data on their front end. In real-time they can transmit the same data in a Chapter 10 Ethernet packet to a Chapter 10 compatible software package like Dewesoft X. Thus meaning that if you have a Receiver that has a built-in Bit Sync (which is required for SOQPSK demodulation) you can then feed the Data and Clock output to your Chapter 10 Recorder. Then the real-time Chapter 10 Ethernet output of the recorder can transmit the data to Dewesoft X Chapter 10 plugin for processing. So in today's modern ground station, you can eliminate a lot of hardware and just have a simple ground station below.

Here is an example of a Dewesoft Telemetry System demonstrated by a big customer.

Analog transmission is not particularly efficient. When the signal-to-noise ratio of an analogue signal deteriorates due to attenuation, amplifying the signal also amplifies noise. Digital signals are more easily separated from the noise and can be regenerated in their original state. The conversion of analogue signals to digital signals, therefore, eliminates the problems caused by attenuation. Pulse Code Modulation (PCM) is the simplest form of waveform coding.

Waveform coding is used to encode analogue signals (for example speech) into a digital signal. The digital signal is subsequently used to reconstruct the analogue signal. The accuracy with which the analogue signal can be reproduced depends in part on the number of bits used to encode the original signal. Pulse code modulation is an extension of Pulse Amplitude Modulation (PAM), in which a sampled signal consists of a train of pulses where each pulse corresponds to the amplitude of the signal at the corresponding sampling time (the signal is modulated in amplitude). Each analogue sample value is quantised into a discrete value for representation as a digital code word. Pulse code modulation is the most frequently used analogue-to-digital conversion technique, and is defined in the ITU-T G.711 specification. The main parts of a conversion system are the encoder (the analogue-to-digital converter) and the decoder (the digital-to-analogue converter). The combined encoder/decoder is known as a codec. A PCM encoder performs three functions:

• sampling
• quantisation
• encoding

What is the PCM Plugin?

The PCM Plugin is the plugin that includes the software Frame sync and Decommutation for PCM data sources. These sources can be from hardware including the Dewesoft Frame Sync box, Chapter 10 Plugin or third-party hardware. The PCM plugin source is only needed so that the Plugin knows where that data is coming from. As long as its PCM data it is all processed the same by this plugin.

What Does it Do?

This Plugin will do a full software frame synchronization on the PCM data source along with processes embedded PCM streams. Then the Decom section allows the user to enter individual parameter information along with the scaling units. Then this data can be combined with many other data sources brought into Dewesoft X software as long as the time source is all the same.

Where Can I Get It?

The Dewesoft X PCM Telemetry plugin and it's manual can be downloaded and tried for free from our Download Center -> PCM Telemetry Plugin.

How to start?

After the Dewesoft X software has been properly installed, you must set up the PCM Plugin within Dewesoft X. To do this, please run Dewesoft X. Go to the Settings menu in the top right of the screen and then select Settings again. When you do this, the Settings dialog box will appear.

Click on the Devices button and you will see the list of all the Devices you can add to your software. If you open this screen and you do not have anything listed please refer to the steps below. Select the Chapter 10 and PCM options from this screen.

Image 21: Add the Chapter 10 and PCM devices 

• Make sure you've selected to install all the Addons when running the installer. You can check by finding your Dewesoft X folder on your hard drive. Then look in the Bin/X3/Addons folder. If this is empty please re-run the installer.
• If your Addons folder has files in it please hit the register plugins at the bottom of the hardware settings screen. *Note depending on IT restrictions you might have to exit the software and run it as an administrator.

Locate the PCM plugin in the list and select change the unused to used to activate it. The PCM Card source selector gives you the option to choose from No device, Test mode (replay mode), and Tarsus PCM card, Chapter 10, Dewesoft USB, and iNet:

1. No device - This is for when you have no PCM source at all and wish to see the setup screens for the PCM plugin.

2. Test Mode - This is an Engineering troubleshooting tool with another ventors binary image file.

3. Tarsus PCM Card - This is for when you have a Tarsus card from Ulyssix Technologies, Inc. installed and want to process raw PCM data

4. Chapter 10 - This is for when you want the PCM plugin to look at the Dewesoft Chapter 10 plugin for its PCM data source

5. Dewesoft USB - This is for when you are connecting a Dewesoft Frame Sync device.

6. iNet - This is for when you want the PCM plugin to look at the Dewesoft iNet plugin for its PCM data source

The General settings selector allows you to select several settings to configure the software to your application.

Image 22: General settings of a PCM allows you to select several settings to configure the software to your application 

1. Bit Indexing: allows the user to define the order the bits are counted in the Decom. The options are 15...0, 0...15, or 1...16.

2. Word Count: This setting determines where your frame sync pattern falls in your word count. The options (FS)1…N means the first word after frame sync is word 1 in the minor frame. (FS)3...N describes the first word in the frame sync pattern as word 1.

The last thing to set up the software is going to Settings and selecting User interface. Please make sure that time format is set to Telemetry (UTC).

Go to the Ch. setup screen either by clicking the Ch. setup tab in the top toolbar or by pressing F2 on your keyboard. The setup screen will be shown. Click the PCM tab and then press the Bit sync button.

Image 24: Click on PCM tab and press the Bit sync button 

On this screen, you set up the channel source information. Depending on your data source the options might change. With the Chapter 10 input source, you will be able to load which PCM channel source and set up the bit rate unless it is in the TMATs section of your stream. Then you can click the Load Settings from Channel button. This will set up the data and frame sync information if it is included.

If you are using the Dewesoft Frame Sync box you will need to tell the software a little bit more information about your stream including bit rate, code type, polarity, etc. The Eye diagram will give you simulated graphics when looking at chapter 10 and then it will be a scope of the data when working with any other hardware.

If there are multiple PCM channels sources inside a single system they will run and are set up independent of each other. Each stream can be selected by the drop-down menu shown below:

Image 25: Select the input source and confirm with Load Settings from Channel button 

Eye Diagram

This display shows the incoming PCM stream in the classic "eye diagram" graph (Simulated in Chapter 10 mode).

Image 26: Incoming PCM stream in eye diagram 

Using the Persistence selector, you can set how many plots are kept on the screen at once. The default setting is 25 and generally provides the best visual reference. You can increase the persistence to 50 or 100, but this takes more computer memory and also takes longer to update the display. The recommended setting for most applications is 25.

Use the Pause button to temporarily freeze the eye diagram for visual study. Press this button again to resume the display updates. The used button allows you to view your eye pattern in a 2D Graph in measure mode.

Waveform Diagram

This display shows the incoming PCM stream (Simulated in Chapter 10 & iNet mode) in a conventional Y/T (amplitude versus time, i.e., oscilloscope type) graph, where the amplitude is shown in percentage, and time is shown in milliseconds (ms):

Image 27: Incoming PCM stream in waveform diagram 

You can hover the mouse over the waveform and the display will calculate the amplitude (vertical Y-axis), the time (horizontal X-axis), and show them numerically at the bottom of the graph.

FFT Diagram

This display shows the incoming PCM stream (Simulated in Chapter 10 & iNet mode) in an FFT (magnitude versus frequency, i.e., FFT/spectral) graph, where the magnitude is shown in decibels (dB), and the frequency is shown in Hertz (Hz, kHz, or MHz)

Image 28: Incoming PCM stream in an FFT diagram 

You can hover the mouse over the waveform and the display will calculate the magnitude in dB (vertical Y-axis) and frequency (horizontal X-axis) and show them numerically at the bottom of the graph.

You may select the window type for the FFT display and the zoom level from the drop-down menu.

Rectangular does not influence the FFT decomposition at all, while the other selections are industry-standard algorithms used for biasing the lobes of the FFT analysis in order to improve the calculations based on different signal types.

Reference Bar

At the bottom of the bit sync setup screen is a reference bar which shows some important parameters:

Image 29: Reference bar 

The core elements, shown here, are also shown when you change to the other setup screens. These include:

• Info ON/OFF indicates which stream is being monitored.
• Bit rate shows the bit rate for the selected stream.
• Signal strength shows the strength as a percentage for the selected stream
• Bit sync shows the status of the signal lock on the selected stream.
• Polarity shows the current polarity (Normal or Inverted) for the selected stream

The headers of the parameters called Bit rate, Sig strength, Bit sync, and Polarity are actually buttons that can be clicked.

Any of these parameters whose header button is pressed in will become available channels in the Dewesoft X display screens under the status folder of each card. This allows you to display it on the screen in a digital meter, status display, tabular display, recorder window, or in any of the graphical display widgets available within the software.

Go to the Ch. setup screen either by clicking the Ch. setup tab in the top toolbar or by pressing F2 on your keyboard. The setup screen will be shown. Click the PCM tab then press the Frame sync button.

Image 30: Click on the PCM tab and press Frame sync button

On this screen, you define the framing of the data within the PCM stream including the data length, frame format identifier, and any asynchronous embedded streams that may be present within the data. Other important settings include the frame lock criteria of the major and minor frames.

"Write Frame to Channel or Stream TAD file while storing" Only use if not in Chapter 10 source. Use these checkboxes to tell the software to automatically archive data to the hard drive in a TAD (Ulyssix Data format) and/or C10 (IRIG Chapter 10 format if system is licensed) format file when storing is underway.

Image 31: Select Chapter 10 source

 

Skip bytes - this checkbox allows you to set a number of bytes to keep and skip, if you have a section of the PCM data which should be ignored.

Image 32: Skip bytes allows you to set a number of bytes to keep and skip 

When you check the Skip bytes box, two fields labeled Keep and Skip will appear automatically. Simply click into these fields and enter the appropriate number of bytes. The byte count starts at the first byte in the frame sync pattern.

Templates - these are a time-saving method of saving a commonly used frame configuration for the frame sync. If there is a template available under the selector, simply choose it and then click the Load button in order to make it active.

Image 33: If there is a template available under selector, simply choose it and click the Load button 

Or, to find another template to load, click the down arrow connected to the Load button, and this submenu will appear.

Moving into the Frame setup table to define the total number of bits in the frame sync pattern from 16 to 33 bits. In image 34, default value was 24 and we have changed it to 32. To change this value, simply click into the field and edit the value shown on image 34.

Image 34: Define the total number of bits 

If you are using the IRIG Standard frame sync patterns the hexadecimal value will be automatically filled in. To change this value, simply click into the field and edit the value.

Select the Use Mask to set up a mask value that will cause the frame sync to ignore certain bits of the sync word. If using a mask enter a mask value using the following logic rules: logic high or '1' in any bit position to ignore that bit. For example:

Sync word size: 32 bits

Sync pattern: FE6B2840 ( in Hexadecimal)

Mask value: 0000F000 ( in Hexadecimal)

This example will cause the Frame Sync to ignore bits 12 through 15 during sync detection. Any value in the PCM stream where the '2' in the FE6B2840 pattern is located would cause a valid frame lock.

Image 35: Sync pattern 

Now enter the number of minor frames per major frame (we have entered 63 in the image 36). Simply click in the field and enter your number.

Image 36: Click in the field and enter your number 

Now enter the Last word number in the minor frame (we have entered 160 in the image 37). Simply click in the field and enter your number. Also, enter the number of Bits per word by clicking in the field and typing the correct value. We have entered 16 on the image 37. This setting is dependent on the Word Count setting under the Hardware Setup.

Image 37: Enter Last word number in the minor frame and change Bits per word from 8 to 16

If your frame definition has variable bits per word simply click on the Bits Per word label. Then the screen will open below to set up your word size. *Note: you can copy/paste from excel to make entry easier.

Image 38: Click on the Bits per word label and set up your word size

To configure the Sub-Frame Sync select either SubFrame ID counter (SFID), Frame Code Complement (FCC) or No minor frame sync (None).

Image 39: To configure the Sub-Frame Sync select either SubFrame ID counter (SFID), Frame Code Complement (FCC), or No minor frame sync (None)

 

Setup the SFID by entering the number of the word location in the frame of the SFID word. For example, if you have a 32-bit frame sync pattern with 16-bit words and the SFID is the first word after sync then the start word is 3.

Image 40: Setup the SFID 

Then enter the start bit in the SFID word and the total number of bits.

Next, select the word order, up or down, using the toggle button. If it says Up, clicking it will change the direction to Down, and vice versa. Notice that the numbers will flip around to match your selection. In the image 40 above, we have selected Up, and therefore the numbers count up from 0 to 63. If we select Down, the numbers flip around to count down from 63 to 0:

Frame Format Identifier (FFI) word is used to allow the decom hardware to identify a unique pattern in the PCM stream and perform a format switch.

If your data stream has one or more frame format identifiers (FFI's), you need to check this box and then enter the integer value corresponding to the word location in the frame, and then enter the word length in bits, appropriate to your data:

Image 41: Check FFI checkbox if you have one or more FFI's

 

When you put a checkmark in the FFI box, you will be prompted to enter the integer value of the FFI:

Image 42: Enter the integer value of the FFI 

We have entered 129 into the dialog box, and then clicked OK to set this FFI value.

Enter the minor frame in which the FFI starts in the Start frame. For this example, it starts in the first minor so we enter 0.

Enter the Interval on how many minor frames must go by before we see the FFI again. In this example, we have a 1 so it will be every minor frame. If we placed a 100 for the interval we would see the FFI every 100th minor frame.

To add another FFI, use the Add button to create one. The same dialog box will appear allowing you to enter the value. As soon as more than one FFI exist, you can use the selector to choose among them, and edit their properties.

If your PCM stream contains one or more asynchronous PCM streams, use the ADD ASYNC button to add each one and then define it.

Image 43: Use Add sync to add one or more asynchronous PCM streams 

When you add an asynchronous stream, you must define where it is in the top-level PCM stream. Enter the starting word and end word by clicking into the fields. If it is not a block of words in between the Start and end word you can use the Super comm to set up an interval.

Image 44: Define the starting and end word 

Use the ADD ASYNC button to add another asynchronous stream or the DEL ASYNC button to delete the selected one. With these controls, you may add and manage multiple asynchronous streams.

Dewesoft X can process multiple asynchronous PCM streams at the same time. To set up each asynchronous PCM frame format use the drop-down menu below to select between the different streams.

Image 45: Set up each asynchronous PCM frame format 

Frame Lock Criteria

Frame Lock Criteria, i.e., the allowed transitions the hardware requires before changing the frame status from search -> check, and then from check -> lock. Then the allowed transitions the hardware requires before changing the frame status from lock -> check, and check -> search. These must be integers representing a number of frames, and normally low values are used of one or greater.

Image 46: Frame Lock Criteria 

Sync window (bits) or also known as bit slips are the number of allowed bit errors in your total number of bits per minor frame.

Allowed sync error (bits) are the number of bit errors allowed in the frame sync pattern to remain locked to the data

Use the Data In Search Mode selection if the user desires data regardless of Frame Lock.

Minor Frame Lock Criteria, i.e., the allowed transitions the hardware requires before changing the minor frame status from search -> check, and then from check -> lock. Then enter the number of allowed transitions the hardware requires before changing the frame status from lock -> check, and check -> search. These must be integers representing a number of frames, and normally low values are used of one or greater.

On this screen, you will set up the system to decommutate the PCM stream. It sets up the software to extract individual parameter data from the PCM stream. The extracted data will be identified, combined, and processed which will then allow the user to visualize and analyze the PCM data.

Image 47: Select Decom tab inside PCM 

Notice the selector which presently says "Main stream" in the image 47. You may use this to select your asynchronous stream (if defined in the Frame Sync Setup), and the channels from that stream will be shown on the main display. Click the selector and then choose the desired stream to define parameters.

Image 48: You can Add or Remove parameters from the decom setup, Copy and Paste parameters, or Import them 

 

The Add/Remove buttons are to add or remove a new parameter to the decom setup.

The Copy/Paste buttons utilize the Windows clipboard to copy selected (the marked or darkened index number) parameters to the clipboard. The user can then paste these same parameters to other cards within the same system.

The Import button is for importing Dewesoft X registered parameter lists for easy loading of parameter setups.

Parameter table heading definitions

Image 49: Import registered parameter lists for easy loading of parameter setup

Parameter Configuration

This is one of the most important aspects of the system because it is where you define the Parameters, or "Channels" which are to be extracted and made available for display and recording within the software.

Image 50: Configuring parameters 

Note - you can turn on or off the raw and scaled output values from each parameter independently. Simply click on the Unused button in the same row as the desired parameter to change it to Used, and vice versa.

Press the Add button to open a new channel setup window or modify an existing channel by pressing the Setup button at the end of each parameter's row.

Image 51: Channel setup window for configuring parameters 

Image 52: Select Data type

Image 53: Decoding and scaling settings 

Scaling values (A0, A1, A2, A3, A4, A5) you can enter the scaling values according to the formula shown below the fields, where: A0 + A1 * x + A2 * x + x + A3 * x * x * x ... Enter as many scaling factor values as you need for this channel; leave the others with the default zeroes in them.

Setting area	Setting	Description
PCM Frame Location - you can set the commutation type and bit locations for this channel. Image 54: PCM Frame Location setting	Commutation Type	Select from Normal, SuperComm, or SubComm for parameter type.
	Interval	Used for your SuperComm or SubComm words. For SuperComm words this is the word interval in between the samples. For SubComm this is the minor frame interval in between samples.
	Bit mapping table	Here you define: Start frame - Is the minor frame number the parameter data starts Start word - Is the word number in the minor frame the parameter data starts Start bit - Is the start bit in the word where the parameter data starts Length - (in bits) of the number of bits in the parameter data
	Bit Concatenation	Where you need to combine bits from different parts of the frame to make one parameter. Ex imbedded Time.
	Use the [+] and [-] buttons to add indices to the bit mapping table. Then you can click within each value in the newly created row or You can also select any index number.
	Use the Trigger index if there is more than one item in a bit mapping table; the user can select what is a trigger index for writing a sample to a Dewesoft X channel.
	Select ET (Embedded Time) to set-up embedded time in the PCM stream as a decom word. The user can define each BCD time digit to a specific nibble in the PCM word.
	Select Synchronous Channel to create a Dewesoft X channel as a synchronous channel, constant rate.
	Select Array channel with channels that have more than one sample (n-m samples, in most cases it is a vector) and is used for special calculations; for example, Missed Distance Calculations
	Values Preview	A very useful tool to look at the values preview at the bottom of the dialog to see the effect of your scaling against the real data. It also gives an overall view of the parameter as you concatenate bits together to build a parameter. Image 55: Value preview
	Use raw and scaled values, these checkboxes serve exactly the same function as the Used/Unused buttons for the raw and scaled outputs from this channel, back on the Decom setup screen. You can also set them here using these checkboxes.

You may import a list of parameters which have already been defined in a TXT, TMATs Files, and CSV import. Click the Import button as shown here on the decom setup screen:

Image 56: Click on Import button to import the parameters list

And you will be presented with the Open dialog box, where you can navigate your computer and locate the file that you would like to load.

The frame preview screen gives you a clean look at the raw live frame dump of the major frame data in hexadecimal. The first minor frame with the minor frame time stamp starts at the top. The channel color labels show your parameter locations in the major frame.

Image 57: Frame preview screen  gives you a clean look at the raw live frame dump of the major frame data in hexadecimal

 

By clicking on a word in the major frame a window will appear giving detailed information on that individual word.

Image 58: If a word in the major frame is not defined as a parameter select the Add New Channel 

If that word is not defined as a parameter select: Add New Channel. This will automatically bring up the decom channel setup screen with the correct frame location information filled in.

A large number of unique and proprietary data structures have been developed for specific data recording applications that required unique decoding software programs. The activities of writing unique decoding software, checking the software for accuracy, and decoding the data tapes are extremely time-consuming and costly.

In the late 1990s, the test ranges started to see the implementation of non-tape-based, high-data-rate recorders, the most predominant of which were solid-state memory devices. Then, as high-data-rate digital recorders were fielded and as solid-state technology began to emerge, the Telemetry Group (TG) saw the need and formed an ad hoc committee for a computer-compatible digital data acquisition and recording standard.

There is a need for a digital data acquisition and recording standard that supports a broad range of requirements, including:

• Data download and interface
• One or more multiplexed data streams
• One or more single data streams
• Data format definitions
• Recorder control
• Media declassification
• Data interoperability
  
  

Specifically, this digital recording standard shall be compatible with the multiplexing of both synchronous and asynchronous digital inputs such as pulse code modulation (PCM) and MIL-STD-1553 data bus, time, analog, video, ARINC 429, discrete, and RS-232/422 communication data.

This digital recording standard will allow the use of a common set of playback/data reduction software to take advantage of emerging random access recording media.

The purpose of this chapter is to establish a common interface standard for the implementation of digital data acquisition and recording systems by the organizations participating in the Range Commanders Council (RCC).

This standard does not imply hardware architecture such as the coupling of data acquisition, multiplexing, and media storage. The required interface levels are contained in this standard.

Image 59: IRIG 106 Chapter 10 Digital Recorder Standard

 

What is the Dewesoft X IRIG 106 Chapter 10 plugin?

The Dewesoft Chapter 10 plugin is a specialized plugin to read a closed recorded data file or a real-time Ethernet stream of Chapter 10 formatted data.

What does it do?

The Dewesoft Chapter 10 plugin will receive the incoming Chapter 10 data stream from a closed file playback from the hard drive or from real-time Ethernet stream. The Chapter 10 plugin will then find the embedded time in the Chapter 10 file to set the Dewesoft master clock too. Then the Chapter 10 Plugin will look at each data channel included in the data stream to then prepare it for processing. For the Analog, Video, and Discrete data the Chapter 10 plugin will put it into the proper data channels for processing and display. It will then hand off the more complex data types like PCM and Arinc429/Mil-1553 data to their appropriate plugins in Dewesoft for further processing to get to the individual measurement channels.

How to start?

If we want to start we need the following files:

• Dewesoft X Data Acquisition Software. You can download the latest version from https://download.dewesoft.com.
• IRIG 106 Chapter 10 plugin for Dewesoft X Software
• PCM Telemetry Plugin for Dewesoft X Software
• Telemetry Camera Plugin for Dewesoft X Software

All the above files can be downloaded from Dewesoft Download Center.

NOTE: To download beta software, free registration and login is required.

Copy all plugin files under Dewesoft folder Addons. Now you can run Dewesoft X, go to Settings -> Devices, and add Chapter 10 extension.

Image 60: Under Devices, add Chapter 10 extension 

In the Chapter 10 Hardware setting there are two modes that the Plugin can run in:

• Recorder Mode: This is where the plugin will acquire data from different sources in the software in real-time. Then Dewesoft X will either record this data to the hard drive of the computer in a.CH10 file format or can real-time transmit it out the Ethernet stream in a Chapter 10 defined packet structure for other devices to receive.
  
  
• Reproducer Mode: This is where the plugin will read in a Chapter 10 format data stream to process the data within Dewesoft X. The Input Type of Chapter 10 file is to read a. CH10 file directly from the hard drive of the computer. The other input type of Ethernet: is to bring in the Chapter 10 Ethernet packet from another device in real-time for processing.

Image 61: Select the device type
 

Then go to Channel setup and go to Chapter 10 tab. This is the screen that appears:

Image 62: Go to Channel setup and click on Chapter 10 tab 

As you can see on the image 62, the file was not found. What we have to do next is to:

A) Select our ch10 file or multiple files (that have the same setup),

This is done by hitting the + button to add files and the - button to remove unwanted files. If using the multi-file playback then the Up button can be used to reorder the files.

B) Choose the start and stop position in the file we want.

This is done so use can playback just a small section of the recording. The "..." button will allow you to set exact times for this. Then uses can replay file at a faster or slower rate. Continuous Loop Mode is for repeating the Chapter 10 file on a loop for playback checkouts. Fast Playback will ignore the speed of the recording and once the user hits the store button Dewesoft X will process the Chapter 10 file as quickly as the computer can to a DXD file.

C) Add or remove channels, Import Channels and Auto-Scan

The Add and remove allow you to manually define channels in your Chapter 10 file. The Import button will let you load a TMATs file for setup. Then the Auto Scan button will scan the Chapter 10 file for the TMATS built into it to configure the Chapter 10 plugin.

D) Enable wanted channels, change its names or see details in setup. *Note the Time channel must always be selected when playing back any data type.

Image 63: Steps you have to perform in case the file was not found 

NOTE: Packets started to appear in format 0/n, where 0 is the number of error messages out of all messages.

In this way, we can preview and enable any type of channels like AI, Time, UART, discrete, video data, and more. The next chapters will show how to do this.

Analog and Discrete Channels

To enable analog or discrete data packets, we set wanted channels to used:

Image 64: To enable analog or discrete data packets, set the wanted channels to 'Used' 

To present it we go to Measure -> Design mode. We would want to present signals on two different controls: Recorder for analog signals and Tabular values display for discrete signals. We add it to wanted place and assign channels to it:

Image 65: Add recorder, tabular values display and apply channels to them 

Discrete value channel is displayed in Raw scaling (a); on bottom left (b) Binary format was selected from the menu on left (c) and on second display (d) Hex format was selected.

Video Stream

To enable Video stream, add Telemetry video under Add Device -> Camera:

Image 66: Add Telemetry Camera 

Image 67: Added telemetry camera 

After that, go back to the Channel setup and you will see the Video tab is already generated with PCM telemetry cameras inside.

Image 68: Video tab will be generated as you add telemetry camera as a device 

We can preview video stream under Setup. Present a video stream in Measure mode under add Widget we choose Video visual control and assign the Camera 0 channel to it.

PCM Stream

First, enable PCM channels:

Image 69: Enable PCM channels in Chapter 10 tab 

Now we can show PCM channel values in Measure tab -> Design -> Add tabular display data -> select PCM Data channel on right. Enable also Raw scaling and Hex format on in the left section:

Image70: Show PCM channel values in a tabular display widget

Decoding PCM Stream

Dewesoft PCM plugin supports the decoding of the PCM stream.

Go to Settings -> add Device -> and add PCM plugin. Select Chapter 10 as a PCM card.

Image 71: Add PCM plugin and select Chapter 10 as a PCM card 

Click OK, go to Ch. Setup, click PCM icon, select PCM data as Input Channel (it is available if tetelemePCM channel is enabled in Ch.10 setup) and click Load Settings from Channel button to load setting from Chapter 10 file (TMATS settings).

Image 72: Load Settings from PCM Data channel 

Now we can see the Frame sync window:

Image 73: Frame sync 

To add channel go to Frame preview and click on the PCM frame -> Add New Channel:

Image 74: Add new channel in Frame preview 

New window opens where parameters of the new channel can be set:

Image 75: Parameters of the new channel 

Measure

We can view all enabled channels in the Measure tab on appropriate visual control that we can select and present in Design mode. To visualize wanted channels on the displays, we just click on the names on the right panel.

Image 76: To visualize wanted channels on the display, click on the names of channels on the right panel 

Additionally, we can add live mathematics, or in Analysis mode on all channels under Ch. Setup -> Math.

In the end, stored channels can be exported in various formats that Dewesoft X supports.