Aerospace Telemetry (IRIG 106 PCM & CHAPTER 10 intro)

Telemetry is an automated communication process by which measurements are made and other data collected at remote or inaccessible points and transmitted to receiving equipment for monitoring.

TELEMETRY is the process in which object characteristics are measured. This measurements results in transmitting this results to a faraway station where they are analysed 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 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.

Photo copyright

With telemetry, data can be transmitted via air, copper wires or fibre 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 analysed properly.

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

Source: L3 Telemetry West: What is Telemetry

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

This is how the complete Telemetry system looks like:

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.

When we launch a rocket there are many things we need to measure for real time flight control and for future performance developments. These measurement 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 roll 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 optimise the use of the available bandwidth.

Below is the standard frame sync pattern.

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 then 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.

Super Commutation – signal is sampled multiple times every minor frame

Sub Commutation – signal is sampled 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 sub frames

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

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.

With Time division multiplexer (TDM) each channel gets sampled for an instant by the multiplexer. When wheel rotates for the first time it samples the data from each sensor and writes it to the memory - puts it into first minor frame. Then the sequence starts all over again. We need to make sure that it always makes full lap. This lap needs to be done fast enough in order to keep 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.

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.

Standards can be found on this link:

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

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 real time. The obstacles and challenges in dealing with the RF world are beyond the scope of this tutorial. Lets move onto the ground side.

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 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 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).

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.

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.

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.

This allows for 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 hundred of parameters to setup. For this 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 setup 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 are 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

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 an 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 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 imbedded 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 setup 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.

1. 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.

2. 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 trouble shooting 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.

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 tool bar or by pressing F2 on your keyboard. The setup screen will be shown. Click the PCM tab and then 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 setup the bit rate unless it is in the TMATs section of you stream. Then you can click the “Load Settings from Channel” button. This will setup 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 setup independent of each other. Each stream can be selected by the drop down menu shown below:

Eye Diagram

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

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):

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 a FFT (magnitude versus frequency, i.e., FFT/spectal) graph, where the magnitude is shown in decibels (dB), and the frequency is shown in Hertz (Hz, kHz, or MHz)

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:

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

  • Info ON/OFF this 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 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 tool bar or by pressing F2 on your keyboard. The setup screen will be shown. Click the PCM tab then press the 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 check boxes 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.

Skip bytes - this check box 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.

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.

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 the example below we have entered 32. To change this value, simply click into the field and edit the value shown here.

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 setup a mask value that will cause the frame sync to ignore certain bits of the sync word. If using 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.

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

Now enter the Last word number in the minor frame (we have entered 160 in the screen shot below). 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 in the screen below. This setting is dependent of the Word Count setting under the Hardware Setup.

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

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.

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 screen shot 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:

A 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:

When you put a checkmark in the FFI box, you will be prompted to 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.

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 setup an interval.

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 setup each asynchronous PCM frame format use the drop down menu below to select between the different streams.

Frame Lock Criteria

1. 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.

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 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 analyse the PCM data.

Notice the selector which presently says "Main stream" in the image above. 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.

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

The Copy/Paste buttons utilize the Windows clip board to copy selected (the marked or darkened index number) parameters to the clip board. 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

Index - is the number from 0 to n (the total number of channels plus one) of the parameter

On/Off - the used/unused status of the scaled output from this channel (when set to "Used", it can be displayed and recorded)

On/Off Raw - the used/unused status of the raw (unscaled) output from this channel (when set to "Used", it can be displayed and recorded)

C - (color) the color of this channel. It can be set here by clicking the color icon or on the Channel Setup screen

Name - is the name of this channel. It can be set here or on the Channel Setup screen

Word - is the word number in the minor frame of this channel

Start frame – is the start frame of this channel, will be a number unless the channel is set to "Normal comm" instead of subcom or supercom

Rate - is the update rate in minor frames of this channel

Size – is the bit length of this channel

Values – are a preview of this channel, scaled against the min/max values

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.

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.

Channel Info : here is where you can set up the top level properties of this channel.

Name - enter a name for this channel. This is what will be displayed in the caption in measure mode

Description - (optional) enter additional info about this channel

Units - enter the engineering units for this channel (V, A, degrees, PSI, etc.)

Colour - click this windows widget to set the colour for this channel.

Delay - enter the number of milliseconds that this channel is delayed by

Min value - set the display scale for this channel: low side (This is for Auto Widget setting along with Overload indicators)

Max value - set the display scale for this channel: high side (This is for Auto Widget setting along with Overload indicators

Note - the min and max values have no effect on the data being recorded. These fields only set the default display scaling.

Decoding and Scaling: here you set up how this channel is interpreted by the software.

Date Type - This is how the data word extracted from the PCM stream is represented in memory. When Two’s Comp or One’s Comp is selected, the data will be represented as positive and negative values. These values will be sign extended when extracted from the PCM stream. The Binary selection will treat data as positive binary values with no sign extension.

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.

PCM Frame Location: you can set the commutation type and bit locations for this channel.

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 bitmapping 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’s 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 vector) and being 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. Also gives overall view of parameter as you concatenate bits together to build a parameter.

Use raw and scaled values, these check boxes 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 check boxes.

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

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 hexadecmial. 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.

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

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 which 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 predominate 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 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.


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 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 latest version from

- IRIG 106 Chapter 10 plugin for Dewesoft X Software

- PCM Telemetry Plugin for Dewesoft X Software

- Telemetry Camera Plugin for Dewesoft X Software

All 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’.

Run Dewesoft X, go to Settings > Devices and 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 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 recieve.

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 real time for processing.

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

As you can see, 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 repaly 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.

NOTE: Packets started to appear in format 0/n, where 0 is 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. Next chapters shows how to do this.

Analog and Discrete Channels

To enable analog or discrete data packets, we set 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:

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, enable ‘Telemetry’ video under ‘Hardware setup’ > ‘Video’:

After that we need to go to Chapter 10 setup and enable Video Data channel.

Video channels are now seen under ‘Video’ tab:

We can preview video stream under ‘Setup’.

Finally we present video stream in Measure mode under Design: we choose ‘Video’ visual control and assign ‘Camera 0’ channel to it:

PCM Stream

First we enable PCM channels:

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

Decoding PCM Stream

Dewesoft PCM plugin supports decoding of the PCM stream.

Go to Settings > Hardware setup > Plugins and enable PCM plugin. Select ‘Chapter 10’ as 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):

Now we can see the ‘Frame sync’ window:

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

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


We can view all enabled channels in ‘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:

Additionally we can do mathematics live 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.

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