Local Email with Winlink Express and VHF FM

              In the after action reports coming out of Puerto Rico after it was devastated by Hurricane Maria, there was discussion on how issues arose trying to moving tactical email between local station in Puerto Rico.  Through a lack of training, the operators were using WinMor links to the Mainland first to send the message, and then back again.  The operators also complained that the issued equipment was HF/50 Mhz only, which inhibited using the radios for local email.  Unfortunately,  the issued equipment was up to the task, but the operators were not.

              Winlink Express offers the ability to use all of their radio modes over FM channels, and 50 MHz and 29 MHz FM offers point to point communications that were required.  Antennas are small enough on both bands that they can easily be made with any locally sourced wire.

              These issues lead to some experimentation in Luzerne County, PA ARES using Winlink Express and FM modes on 2 meters.  While 2 meters was used, 6 or 10 meters would have been equally effective.  At first attempts were made to establish AX.25 1200 baud packet.  Winlink Express allows hardware and software modems to be used.  I was able to establish links using a Kantronics 9612, SCS Tracker, and SCS DR-7800.  The most difficult issue was discovering the COM port as well as the proper baud rate.  The 9612 used a 4-way FTDI chipped Serial to USB adapter.  Finding which input (it was #2) was the first challenge, and then setting the comms baud to 9600 on the COM port listed in device manager.  This modem worked at both 1200 and 9600 baud as it is a dual port modem.  The SCS Tracker is a natural USB connection and used 38400 Baud at the listed COM port and was relatively easy to install.  The 7800 used 57400 Baud and was also easy to set up in Winlink Express.  Both of these modems are capable of high speed links, but setting the deviation of the radio at these speed as well as the very high signal quality required makes working these speeds difficult.

              To send local email in Winlink Express, open up the Packet P2P session and go to the settings option.  There is a drop down menu for they type of modem.  You can just enter the modem type, add the COM port and Baud rate, and then hit “update.”  This should enable the modem without changing any other settings. Type in the target station, even through a digipeater, and the monitored frequency and hit the connect button.  This should start the exchange process which will work without further intervention from either user.

              The cheaper TNC option is the use a soundcard modem for packet.  I use the SoundModem by UZ7HO.  In this program you set the radio to AFSK AX.25 1200 Baud and a center frequency of 1700.  In the Settings Devices menu, first you select your input and output devices.  The settings for an external soundcard device such as a Signalink or built in soundcards in a radio will be the USB codec setting.  If you are using the computer’s soundcard, you will probably will keep them at the default.  You have to uncheck the AGWPE Server Port and check the KISS Server Port of 8100.  Also you should check TX Rotation, Single Channel output, Color Waterfall.  The PTT settings depend highly on your controller.  Using the Signalink controller, you keep the PTT port to NONE.  If you are using a COM port keyed PTT as many Rigblasters do, you need to set the COM Port properly.  In the settings Modem, you keep the default modem filters for Channel A, check the ALL filter, and check KISS optimization and non-AX25 filter.  Keep the program running, either in a window or minimized.  I prefer the window open to monitor the packets and waterfall.

  In Winlink Express, open up Packet P2P window and go to the settings.  Use the modem drop down menu and select KISS.  For COM port you need to set it to TCP which will open up boxes for the IP address and Port.  Keep the default IP address of 127.0.0.1 and select port 8100.  Switch the TNC mode from NORMAL to ACKMODE.  Keep the TNC parameters at the default but check Enable IPoll.  Hit update and it should give you the ready command in the main box.

The trouble we had in the Luzerne County experiments was using Packet in general.  The signals were strong, but 30-50 watts was required to make links.  Due to our location, RF was bouncing off the hillsides like a pinball and there was significant multipath.  AX.25 fails completely in the presence of multipath and we had link establishment failures no matter what modems were being used.  Also, high power isn’t conducive to field operations.  A better solution is required.

The first option we explored was Winmor 1600.  This is designed as a HF protocol, but can easily fed into an FM circuit via a soundcard.  A 3 KB email was exchanged at 1574 Bytes/minute using the fastest mode.  Unfortunately, the overhead packets are sent at much slower speeds.  The big advantage in using Winmor is that there is really no set up required, the default settings in the Winmor P2P window worked flawlessly.  This makes it very field deployable with little training required.  Using this mode on 10M FM in Puerto Rico would have been the way to go.  One caution is when using Icom HF/VHF radios, the 2M FM side of the radio uses a dedicated VHF PTT pin, so the cable will need to altered or replaced.  This is not an issue with Yaesu.  I do not know about other brands.

LCARES makes extensive use of the FLDigi suite of programs.  FLARQ offers an email function through FLARQ, but the email program is very primitive and not as intuitive as Winlink Express.  The next stage of this experiment is use the high speed modems in FLDigi to move email from Winlink Express.  Fortunately you can set up FLDigi to accept KISS inputs, so after adjusting settings, you can set the data packets over FLDigi modems. 

In FL Digi go to Configure, Miscellaneous, IO.  Uncheck “Lock” then check Enable KISS (NOTE: THIS WILL DISABLE FLARQ as it can only work as a server for ARQ or KISS.)  Check TCP/IP, Listen/Bind AX25 Decode, Auto Connect/Retry, and Inhibit 7bit modem.  I set the IP address to 127.0.0.1 Addr to 8100 I/O and 8101 O.  Next hit save, and restart FLDigi (the port settings will only take effect when you restart FL Digi.)  Select the modem you wish to use.  Since it’s an FM circuit, you should use modes like 8PSK1000F or 8PSK1200F.  The key is that you cannot use 5 or 7-bit modems as it is 8-bit data being moved.  Due to the turn around times required for KISS packet exchange, most of the FLDigi modes can’t be used, as their preambles are too long.  For best results use 8PSK1000F.  I turn off TXID as the header will be sent with every TX and greatly slows the exchange.  Have a pre-determined mode and center frequency (1500 is good for the fast modes) monitored on both sides of the link  I also turn off AFC and SQL in FL Digi.  RXID can be on or off.  Leave FLDigi running.

In Winlink Express, open Packet P2P Go to Settings.  The settings need to be changed due to the nature of the modems.  For TNC settings on 1200 baud the following were used:

RFBaud 1200

Max Packet length 64 (standard 128 bytes takes too long and the Rx station attempts to send the ACK before the packet has been transmitted.  This was a major stumbling block for us)

Max Frames: 2 (same issue as above 4 frames only work with AFSK packet)

Frack 2

Persistance 160

Slot time 30

Max Retries: 5 (this is up to the user, but for FM, it shouldn’t need to be any more)

Enable IPoll 

You can now establish the link with the FLDigi modems.  Just like Winmor, this should fight multipath far better and require much less power.  During our testing, when we needed 30 watts for packet, we could reduce power to 5 watts for Winmor link with no loss of speed.

During testing we actually found 8PSK1000F a bit faster than the 1200 baud variety, even with no packet repeats.  Throughput for data on 1000F was 2277 Bytes per minute, while 1200F was around 2100 B/Min.  I am at a bit of a loss as to why this is, unless the 1200F uses more check bits and therefore fewer data bits per packet.  Both of these modes were significantly faster  than Winmor 1600.

Testing was done on 2 meter FM simplex at a LOS distance of about 10 miles.  Antennas were base models, but not directional and full scale signals were received at 5-10 Watts.

In conclusion, the proof of concept works, and there are several ways to move P2P mail between stations on VHF simplex.  The choice of modes will depend on the link scenario and equipment available, as well as the skill of the operators.  Cost for the basic setup is minimal, requiring only a radio with antenna and soundcard interface, but it will take some dedication to set up and use the equipment.  This system will not replace the excellent multi-point broadcast capabilities of FLDigi (especially in conjunction with FLMsg and FLAMP).  This is another tool in the box, but probably will be on a lower shelf.

HAL ST-8000A Wiring and Pin-out

              Probably the toughest part of using the HAL ST-8000A is wiring up the unit in the configuration that you want to use it.  As mentioned in the introduction article, you have four options to run the unit.  The first is to use it as designed, where audio is fed into the unit, demodulated, and exported as RS-232.  The second option is similar, but uses MIL-188 data output.  The third option is for the terminal unit to “regenerate” the audio and output Mark and Space tones for further decoding.  The fourth is one that isn’t clearly documented, and has the ST-8000A filter the input audio, and then output the audio to the Data I/O connector before it is demodulated at all.  Of the four modes, the last holds the most promise for effectively using the ST-8000A in the 21^st century.

              In this article, I will review the pin outs for using the unit as a regenerator and as a filter, as both can be done simultaneously.  To use the rig to output serial data, the number one port needs to be configured away from regeneration, so I have not pursued those options.

              The first step is to open the 8000A and set some of the jumpers.  Just remember to have the unit turned off and unplugged.  It is also advisable to take proper static precautions when reaching into the interior.  There are quite a few options, most of them dealing with the remote control and RS-232 parameters.  Details of these are in the manual, but since I was not using these functions, I did not adjust them from factory defaults.  The first jumper I set was the input impedance jumper (A1J6) in the upper left corner of the unit.  Since my Icom 746 has an audio out impedance of 4.7 kilo-ohms, it made for less of a mis-match to set it to 10 kilo ohms rather than the default of 600 ohms.  The second jumper I set was for the tones mute (A1J8).  To use this unit in regeneration mode, this jumper must be changed from the factory default so that the tones are always on.  This fact was confirmed in an email from HAL Communications.  Once these two jumpers are set, then you can re-install the top cover and get the soldering iron ready.

              There are three sockets in the back of the ST-8000A.  They are marked Audio I/O J2, Data I/O J1, and Remote.  I do not use the remote socket, as I change all parameters from the front panel.  The Audio I/O port is a MS27508E14F35SA connector which is female.  You will need a MS2743E14F35PA Male connector to mate with it.  These are available for about $40 online if you are missing the original.  The socket has 37 pin possibilities, but fortunately we won’t be using most of them.  Soldering them is pretty easy, as you solder the pin to the control cable, and then insert the pin into the socket using a special tool which comes in the accessory pack.  The audio in and out are via balanced lines.  Ground pins 3 and 12 if you are feeding an unbalanced line, which is what you are normally going to do.  The manual states to ground them at the radio.

The Audio I/O Jack has the following pinouts: (if a pin isn’t listed, it’s not connected)

 Pin 1 Modulator FSK Audio Output (AFSK out) rated -30 to 0 DBm 600 ohm

Pin 3 Modulator FSK Audio Output (AFSK out) rated -30 to 0 DBm 600 ohm (ground this if you are feeding an unbalanced system)

Pin  5 Keyline relay contact (PTT) +50V, 0.2A max

Pin 6 Keyline relay contact (PTT) +50V, 0.2A max

Pin 8 jumper wire to J1 Pin 8, 200V 5A max

Pin 10 Demodulator FSK Audio input (Audio In from line) -45 to 6dBm, 600 or 10K ohms

Pin 12 Demodulator FSK Audio input (Audio In from line) -45 to 6dBm, 600 or 10K ohms (ground this if you are feeding an unbalanced system)

Pin 37 Shield (ground)

              For my setup, I ran two sets of XLR balanced audio lines from the plug that then allows me to use adapters for various audio inputs.  I am generally using HAL DSP controllers which use RCA plugs, so I have XLR to RCA adapters for most of the work.  I only utilized Pins 1, 3, 10, 12, and 37 for my setup.  Running the PTT via Pin 5/6 would be required for normal operation, but not regeneration or filter mode, as the 8000A isn’t used to transmit anything in these latter modes.

 The second socket is Data I/O J1.  The socket is type MS27508E14F35SB and the male plug required is a MS27473E14F35PB. 

              The Data I/O jack has the following pinouts:

Pin 7 Demodulator undetected Mark, 0 dBm Mark audio (this is the filtered audio output)

Pin 8 Jumper wire to J2 Pin 8

Pin 9 Demodulator undetected Space, 0 dBm Space Audio (this is the filtered audio output)

Pin 10 is the carrier detect output (+/-6 VDC selected by jumper A1J9)

Pin 12 Demodulator Analog Ground (use this as the ground return when using pin 7 and/or 9)

Pin 13/14 ground

Pin 15/16 Keyline Relay contacts +/-50 V, 0.2A max

Pin 17 Data I/O RTS Input +/-18 V RS-232

Pin 18 Data I/O CTS output +/-6 V RS-232

Pin 19 Transmitter clock output +/-6 V

Pin 20 Modulator Digital Data Input +/-18 V RS-232/MIL-188 (Jumper to Pin 22 for Regeneration Mode)

Pin 21 Demodulator Mid-BIT clock output +/-6 V RS-232

Pin 22 Demodulator Digital Data Out (RS) +/-6 V RS-232

Pin 23 Demodulator Digital Data Out (MIL) +/-6 V MIL-188

Pin 24/36 Modulator Analog Ground

Pin 25/26 Ground

Pin 37 Shield (Ground)

 The Data I/O port has more connections, but we use very few of them in Regeneration or filter mode.  Getting REGEN audio out of the ST-8000A proved to be a big stumbling block for me.  I resorted to emailing HAL, and they told me to be sure to jump pins 20 to 22 in this plug to route demodulated audio back into the modulator to get it to loop effectively.  This is in addition to turning on the REGEN function on the front panel.  Once this jumper was installed, I was in business.

              I was intrigued by pins 7 and 9 when I read the manual, especially this passage:

              “The demodulator undetected outputs signals (MARK = Pin 7, SPACE = Pin 9) are usually not connected to data terminals.  These are filtered audio signals recovered from the demodulator input signal.  These signals may be used for further data processing or for connection to an external tuning display (oscilloscope)… The external load to ground on Pin 7 or 9 should be 10K ohms or higher.”

              This passage got me thinking.  Can I extract audio from the ST-8000A and run it through a DSP box and have the DSP box do the decoding?  Better yet, can I split the audio and have it run to and external tuning unit AND have it run to a DSP decoding box as well?  I posed the question to HAL and the response was “I hadn’t thought of using Pins 7 and 9 in this way. I can’t think of any reason that it won’t work.  It is a pretty high level output so I don’t think it will cause any problems.”  The short answer is, yes you can, and it does work.  As a caveat, I did use audio isolation transformers to isolate all the various hardware components.

              The plug wiring is pins 7 and 9 are run through an XLR plug via shielded audio cable; Pin 7 on the 8000 is Pin 1 on XLR, pin 9 is Pin 2, and Pin 12 is Pin 3.  This then runs one of two pigtails.  One pigtail converts the XLR to RCA by wiring both data pins (1&2) to the tip, and ground (3) to the ring.  This runs through a Y-adapter and then each leg run through a 1:1 isolation transformer.  The audio feeds a HAL  DSP-4100 for DSP processing and decoding, and the second leg goes to a HAL DXP-38 for tuning indication.  I also have a pigtail that sends each audio signal via coax to BNC connectors for an X-Y display oscilloscope.  The use of the scope would currently require me to use the unit in Regeneration mode, as the audio signals are never joined.  I have also successfully run the audio solely to the DXP-38 for tuning indication and decoding.

I used a simple wire jumper in the plug to connect Pins 20 and 22.

              The audio in section I saved for last.  I run two audio cables to the ST-8000A.  The first is audio from my ICom 746 using the ACC(1) port pin 5.  This has a fixed impedance of 4.7K ohms and level of 100-300 mV.  This is more than enough to drive the unit.  I use an audio isolation transformer to block any DC.  I also have a cable running from my computer headphone jack to the ST-8000A.  I checked with my scope to make sure that the audio drive was under 300 mV (a volume setting of <30 on my computer) and the system worked well.  I used this to copy RTTY newswires from www.RTTY.com

              I use the DSP-4100 or DXP-38 for all transmitting work and this is done with the standard FSK keying line into the Icom.  The 8000A is really used only in the receive side of the radio system. 

              That is the wiring of the unit.  The next task will be to set up the front end to get the unit to decode.

HAL ST-8000A Powering up and Internal Testing

Before you purchase a HAL ST-8000A, it would be best for you or the seller to run the internal test procedures to check your firmware and to ensure that everything is still running correctly.  These units are over 20 years old now, and the electronics could start to fail if they have been sitting in storage for too long.  The good news is that this testing is very easy, and only takes the power cable to complete.  So even a NOS unit can be powered up and tested with no technical knowledge about the unit.

              Check on the back panel to make sure that the frequency and voltage match your power mains.  Unlike most TNC’s, the 8000A uses about 30W of AC power and not 13.8 VDC.  In the US this would be 115V and 50/60 Hz.  Europe and Asia require it to be set to 220V and 50/60 Hz.  The frequency switch can also be set to 400Hz for aircraft use in accordance with MIL-STD-704.  If your 8000A has the accessory package, you should be supplied with two power cables, one that is a standard desktop computer cable, and a short adapter that allows the unit to be plugged into military power systems.  The male plug is for the US standard, but adaptors or other cables with the proper female socket will work.

              Once the unit is plugged in, flip the front power switch and the 8000A will go through the first diagnostic check.  During this check the firmware version will be displayed.  The newest firmware is version 1.9.  Once the start up has ended, the unit will show mark and space frequency as well as baud rate, and you should get a slight flicker in the LED bar graphs.  A few of the display LED’s might also be illuminated, depending on the settings.  This is the first test, and the one most ignorant sellers will claim is all they can do.

              The second test is called the BIT test, and this tests the internals of the ST-8000A by routing the modulator through the demodulator to check that the circuits are working correctly.  To perform this test, turn the unit it on, and upon completion of the start up test, hit the “2^nd” key, then hit “BIT” and finally “Enter.”  This will run the machine through a 13 step self-diagnostics test, including testing all the LED’s and testing the demodulator at several audio levels.  If all is well, the unit will end the test by putting “Pass” on the LED display and finally returning to standby mode.  If there is a failure at any point, it will display the step of failure and say “FAIL” on the screen.  The test will not proceed beyond the failure point.

              Once the ST-8000A is verified to be functioning correctly by these tests, it is time to move onto the wiring to be able to get audio into the unit from the source, and then intelligence back out.

HAL Communications ST-8000A Overview

              This will be the first of a series of blog posts on the HAL ST-8000A.  I have had quite an adventure getting one of these terminal units working in my station and there is very little information on the internet to help with the process.  I hope to provide an overview as well as some hints and tricks I learned, or discovered that helped me along the way.  If someone else wants to use this unit in their station, I hope that they can use this information to make the process more painless than mine was.

              The HAL ST-8000A is a teletype modem that was designed for the military to provide a drop-in replacement to the Frederick Electronic 1280A modem.  It can be used in both radio and hardline applications and converts FSK Teletype at a wide range of baud rates to/from either RS-232 or MIL-188 protocols.  Since it was designed for the US Air Force, it uses US Department of Defense Bendix plugs and is built to military specifications.  This means that it is very well build, EMP hardened, and subsequently very costly.  This was HAL Communication’s last terminal unit that did not have a DSP circuit.

              The flow diagram of the unit is as follows: audio is fed through a balanced line into the unit where it passes through a series of filters.  The filters are automatically selected based on the programed front-end settings.  Filter width varies directly with the selected tones and baud rate.  The unit can handle tones from 300 Hz to 3000 Hz, which will handle most radio SSB bandwidths.  There are a series of low pass filters that cut out noise and then the audio is routed both the I/O port (more on this later), and one of two individual discriminators. The first discriminator is used at baud between 30 and 600 baud, and the second for baud rates from 601 to 1200.  The discriminators decode the audio input and uses a microprocessor to convert it to one of three digital signal outputs: 1) RS-232 data, 2) MIL-188 data, or 3) audio tones (Regeneration).

              On the transmit side, the ST-8000A will take data input (RS-232 or MIL-188) and convert it to AFSK tones which will drive the SSB radio or pass it over hard lines.  This is very similar to how most sound card and many TNC’s are utilized to send RTTY.  The unfortunately part of this is that you cannot use the FSK mode on the radio which is disadvantage on many radios due to the filter limitations while in SSB mode instead of RTTY mode.

              Using the ST-8000A as designed will require the appropriate software to decode the RS-232 or MIL-188 data streams in to text.  Given the age of these units, the terminal programs will be difficult to find, and will need to use older operating system emulators to run the software.  Add to this the lack of DSP and the use of AFSK on the transmit side, you may wonder why you would bother to use an ST-8000A in the first place.  The answer to this is the front-end filters.

              When people still used the ST-8000A, or it’s civilian cousin the ST-8000, the operators were looking for a way to use the superior decoders on the ST-8000’s while using their favorite software, which often did not interface with the terminal units.  The stop gap measure was to use the “regeneration” feature of the 8000’s.  This had the 8000 decode the audio with it’s superior filters and discriminators, and then convert them to pure, high S/N ratio audio signals to be converted to data by a secondary TNC which fed data to the software.  Any TNC was able handle the high-quality signals from the regenerator, and then the secondary TNC could be wired to send FSK signals to the rig, overcoming the second issue of the 8000’s.

              With the utilization of DSP, this stop-gap use of terminal units was rendered obsolete.  While some newer TNC’s use DSP, it was pointless to input regenerated tones into them, as the regenerated audio did not need further processing.  In standard soundcard interfaces, software was able to take audio directly from the radio and DSP algorithms were superior to the discriminators to the 8000’s.  Some software and interfaces could even overcome the FSK keying issue and software took over from the terminal units in most applications.  The use of external TNC’s and expensive terminal units essentially stopped.

              My idea in getting the 8000A was to see if I could use the TU as an audio filter and then feed the processed audio into a DSP TNC to take advantage of the filtering of the ST-8000A and then use a secondary TNC to use DSP on the signals, and decode them.  This also allows the secondary TNC to use FSK keying.  This plan could also have audio sent to a sound card interface and so the same thing, but onboard the computer.  This was the challenge that the internet had not seemed to meet as I rooted around for information on the HAL ST-8000A.

              The 8000A was never as popular as the 8000.  A few reasons for this are the fact that the 8000 used standard 25 and 9 pin serial connectors which were easily and cheaply available.  The 8000A uses Bendix 37-pin plugs that are harder to find, and far more expensive.  The other big issue for hams was the lack of dials and the replacement of an analogue tuning oscilloscope with the less popular MARK/SPACE LED bars.  The fact that the Mil-spec 8000A was also considerably more expensive sealed the deal.  Today you can find 8000A’s inexpensively, but the 8000’s are quite rare.  While the interface issue is a matter of preference, there is a way to pull filter audio out of the 8000A and feed it into an oscilloscope for a similar display.  The plugs, while expensive, can be bypassed and refitted because the jumpers between the plugs and the board go into a Molex plug.  Just be sure if you go this way, to ground all of the unused pins or you will get errors. 

                I was able to find a ST-8000A online for a price that I could justify, and had it shipped to me.  The unit had never been wired up, so all the original accessories including the Bendix plugs and pins were included.  Unfortunately, the instruction manual was not in the box.  Fortunately for me, the customer service at HAL is excellent and I had a pdf version of the manual in my Dropbox account which was worth it’s weight in gold.  Now that I had the ST-8000A, I had to research to see if it could do what I wanted it to do, and if it could, how I needed to set it up.  Once I had the ST-8000A in my shack, the real adventure could begin.