The AOR AR9800 could be the
biggest revolution in
HF radio since SSB replaced AM
| General |  |
| Is it legal? | |
| Circuit description | |
| Flash upgrades | |
| Operating
manual & sales leaflet |
|
| ARD9900 encryption | |
| Web review & audio clips | |
| Specification | |
| Frequently Asked Questions |
THE ARD9800 IS OFCOM AND CE APPROVED
The ARD9800 is a modem unit that connects to the microphone input of virtually any transceiver. The user simply wires a connector for his particular transceiver, connects the speaker output of his transceiver to the modem and then connects the modem to a 12V DC power source... no modification is required.
The ARD9800 provides NEAR FM QUALITY audio using SSB. Even better, the digital signals require no more bandwidth than analogue signals, which making operation possible even under less than perfect band conditions.
Normal analogue operation is possible (because the transceiver has not been modified). To use digital voice, simply select the DIGITAL MODE on the ARD9800, incoming signals are automatically decoded, no selection necessary. So, if an analogue signal is encountered, the transceiver operates conventionally, however if a digital signal is encountered, the ARD9800 automatically selects the digital mode so that high quality interference free audio is produced.
The ARD9800 can be used in any mode, SSB, AM and FM, however FM mobile operation could be prone to 'picket fencing' (fast flutter) which could result in the loss of data.
The UK version is also equipped with an IDENT and NET-MASK facility which is not featured in the USA version.
With the optional ME1 memory board, images can be easily transferred, similar to SSTV but we believe the ARD9800 sends a higher quality image. You can also send data file transfers. Currently SSTV images 'out of the carton box' are in NTSC, a PAL version is available.
Owner can use microphone supplied as part of the ARD9800 package, or a microphone of their choice (wired for ARD9800 input). The ARD9800 package includes, modem, microphone, cables, manual. The pin-out of the ARD9800 is to ADONIS standard so that 'off-the-shelf' commercial leads may be employed. A list of leads may be viewed at the following web page (for code number):
http://www.adonis.ne.jp/code.html
Adonis cables may also be obtained from several suppliers in the UK including Martin Lynch & Sons Ltd and Waters & Stanton PLC, refer to the Waters & Stanton 2005 catalogue page 47, prices typically range from £10.95 to £15.95 inc VAT (I - Icom, K = Kenwood, Y = Yaesu):
| D-8MI | Modular Icom plug |
| D-88I | 8 pin Icom plug |
| D-88MK | Modular Kenwood plug |
| D-88K | 8 pin Kenwood plug |
| D-6MY | Modular Yaesu plug |
| D-8MY | Large Modular Yaesu |
| D-88Y2 | 8 pin Yaesu plug |
Yes, the ARD9800 employs an open published digital protocol (Charles Brain G4GUO) per FCC rules. The transmit bandwidth is within the same spectrum as conventional SSB.
CE approval has been achieved and OFCOM has approved the AR9800 for use by Radio Amateurs in the UK from 19 January 2004 under the guidelines of BR68 (open protocol data mode to enhance operation).
For further information visit the OFCOM web site on www.ofcom.org.uk
The data format has been characterised and publicly released as an 'open protocol' on the following web sites:
The ARD9800 is already in use in the USA, and Japanese approval for Radio Amateurs came into effect in January 2004. Some on-air tests are still planned with various CEPOs in the UK.
1. Introduction
The ARD9800 Multi-Mode and Digital Voice Interface is designed to be connected to the microphone input and the speaker output of any HF (High Frequency) amateur radio
SSB (Single Side Band) transceivers.
The following operation mode is available with the ARD9800.
1. Digital Voice
2. Digital Still Picture
3. Digital Data
All digital data are modulated by the OFDM with 36 carrier signals, and each carrier signal are modulated by the DQPSK. The modulated signal has a band width between 300 Hz - 2500Hz. Therefore, no modification will be necessary to use the ARD9800. To convert analogue voice signal to digital voice, the AMBE Vocoder chip, made by the DVSI, Inc, is used to compress the signal with a rate of 2400bps. To send still video image, our original protocol based on DCT is used. It will take approximately 2 minutes to send one frame image. Vide input and output signal is the NTSC. Data transfer can be made in the ASCII mode or Binary mode, and is sent as a data packet. Data error correction is available in the data communication mode.
2. Voice Signal Processing
2-1. Microphone Input
The microphone input signal from the microphone connector is amplified by the Q37
(transistor), and will be fed to the A/D converter through an analogue switch (IC17).
The A/D converter outputs 16 bit of signal data with 16 KHz of sampling frequency.
The output from the A/D converter is compressed by the AMBE2020 (IC6, vocoder chip).
2-2. Audio Input
The speaker output signal from the radio equipment is amplified by the audio IC chip
(IC24) to be monitored. The monitor output level is adjustable.
In the meantime, a partial speaker output signal will be fed to the AGC amplifier
consisting of the IC19 and IC20 to be decoded (OFDM model signal). A signal level of the AGC
amplifier is detected by the CPU (IC1) so that a proper level of signal is obtained to the
circuit. The AGC output will be converted to 16 bit digital signal by means of an A/D
converter. The digital signal is digitally processed by the FPGA (IC2) and the CPU (IC1),
and then decoded.
2-3. Microphone Output
The ARD9800 outputs signals with either modem signal, bypassed analogue audio signal, or
digital voice signal depending on a selected operation mode.
Compressed digital signal through the AMBE2020 (IC6) is converted as OFDM signal
by means of a digital signal processor (IC1 and IC7), and is fed to the microphone output
connector through the D/A converter (IC7). In the analogue voice mode (bypassed mode), microphone input signal is bypassed
through IC7.
2-4. Speaker Output
In the receive mode, the speaker output from the radio equipment has been fed to the
speaker amplifier (IC24) and drives an internal speaker. In the event of validated OFDM signal is detected by the IC1 and IC7, the signal will
be automatically decoded and converted to analogue signal by the AMBE2020 vocoder (IC6).
The analogue signal will be amplified by the speaker amplifier (IC24) and drives an internal
speaker.
3. Video Signal Processing
3-1. Video Input
The input NTSC composite video signal at the connector is fed to the L7, LPF (Low Pass Filter). The signal will be then amplified by a differential amplifier (Q38, Q39, and Q20).
Then the Q14 and Q19 will clamp the composite synchronous signal to keep it a constant
level. The clamped signal will be then converted as 8 bit digital signal by the IC23. The
sampling frequency is 4FSc (14.31818 MHz). The digitally processed video signal will be stored in a video memory through the IC2.During the process, the IC1 will decode the signal and convert the video image into
colour.
3-2. Video Output
The video image in a memory will be fed to the IC2, and convert to a 8 bit composite
signal. The signal is then converted to analogue signal by means of the L8, L9 Q40, and Q41.
4. PC Interface
The ARD9800 has a built-in serial interface for a PC. The serial data from the IC1 will be
shifted to a RS-232C level by the IC18. The input RS-232C serial input data is shifted to a CPU interface level by the Q33, Q34,and Q35. Then the signal will be fed to the serial interface input of the IC1.
Top
Flash upgradeable and on-going comments
The ARD9800 can be flash upgraded to keep the unit 'current' with production enhancements. The AOR UK workshop has been provided with a utility program to enable this via the PC... this utility and firmware updates will be released via the web as a download once the documentation is complete. A utility to handle images will also be supplied for download.
At the beginning of November 2003, the following
enhancements were added:
1. Forced synchronisation
If the digital 'ring' is not acted on by the receiving unit, it is possible
to FORCE the two ARD9800 to resynchronise, so the transmitter is not left talking
to no-one'.
2. Improved level indicator
The front panel LEDs are not actively employed to ensure you have the correct
level of audio drive via the microphone.
Refer to the operating manual addendum.
Comment from the ARD9800 design team
December 2004 (rephrased):
Recent testing of the ARD9800 has been carried out using a "fading channel simulator", as a result new recommendations can be made for better HF performance.
Where fading signals are anticipated, the following commands can be employed:
Cmd>AAU OFF
Cmd>AHL 160
The auto-digital frame detection is the function of capturing digital voice frame without "frame header tone". However, we found this did not work well on HF during heavy fading signals.
If you cancel this auto function, the ARD9800 can be more tolerant of deep HF fading signals.
AAU is the command for enabling/disabling the function of auto-digital voice
frame detection.
I the case of use with an FM radio, AAU ON would be fine.
Note about type of ME1 module when PAL
is used:
There have been two or three different types of memory module employed by the ME1. The early type (before January 2004'ish) and latest type (after September 2004) may be used with either the NTSC or PAL versions of ARD9800 but production between about January 2004'ish and September 2004 is only suitable for NTSC use.
- NTSC only ME1 units employ chips marked by the manufacturer "ST", a white sticker on the PCB may refer to 2003.
- NTSC/PAL compatible ME1 units employ chips
marked "R1LV0408CSB", a white sticker on the PCB may
refer to 2004 or later.
| AR9800 default settings: | |
| SP IN | 10 o'clock |
| MIC IN | 3 o'clock |
| ANA OUT | 4 o'clock |
| DIG OUT | 10 o'clock |
Firmware updates for the ARD9800
Firmware is flash upgradeable via the PC and is supplied in three formats:
1) N9800505A.MOT - latest NTSC beta version for USA only (selectable header type)
2) P9800-5P4A.MOT - latest version PAL < < < UK / Europe
3) N9800504K.MOT - latest NTSC version, non-USA (the "official" NTSC version)
It is VERY IMPORTANT that you do not mix NTSC firmware via PAL hardware and vice versa.
The loader "boot_ARD9800.mot" must be used for NTSC and "boot_ARD9800PAL.mot" for PAL, plus the relevant hex (mot) file.
The following is a summary of what you need to do when updating firmware:
1) Remove connections to ARD9800 and top cover of the ARD9800.
2) Move jumper JP8 from "NOR" (pins 2-3) -to- "PRG" (Pins 1-2).
3) Copy the MOT files and SHBoot.exe into a folder you have created and name it ARD9800Update.
4) Connect Com Port and DC power.
5) Double click SHboot.exe file to execute writing utility.
6) Find "Boot” file selecting area and "...." button then left click "...." and double-click on "boot_ARD9800.mot" file for NTSC or "boot_ARD9800PAL.mot" for PAL.
7) Find "Firmware” selecting area followed by the Boot area then left click "...." and double click on the desired update file (making sure you do not mix NTSC and PAL), for example NTSC in the USA would use "M9800505A.mot" and PAL in the UK would use "P9800-5P4A.mot".
8) Power up ARD9800 (No LEDS will light).
9) Uncheck “Fast Mode with no display” (to see data being written).
10) Now ready to flash memory (takes about 1 min)...Press “Start”.
11) Status of data being sent will be displayed.
12) At the end of the flash process (series of 00s), power ARD9800 off.
13) Move jumper JP8 back to "NOR" position.
14) Turn ARD9800 on. Power up sequence should be normal with "Mode" LED in yellow followed by red then "Over" flashing off and on.
If your want to check the version number, use a communications program (Hyper-terminal @ 9600 baud) and verify
version using command AVR. Note: Remember ARD9800 commands are all in UPPER CASE.
To check version
cmd>AVR
AVR 505A
To set ARD9800 to factory defaults
cmd>APR
APR OK
ALL the current firmware version and loader / utility software is provided in a single ZIP file called ARD9800UPDATE.ZIP right-click here to download it (950kb).
Software downloads
It is possible to download IMAGE TRANSFER software and FILE TRANSFER software free of charge. To prevent issues of "old versions" being made available, they are held on an external (non-AOR) server:
http://www.hamradio-dv.org/aor/digital-ssb/downloads/downloads.html
ARCT9800 is the image transfer software in ZIP format (just over 1MB)
ARFT99 is file transfer software in ZIP format (just under 1MB) - has Japanese characters as it was intended for the home market.
The software is supplied "as is" with no warranty nor formal support.
As well as the picture format being different in Europe (PAL in place of NTSC - still under development), the European version has an IDENT feature. The operating manual here relates to the UK version.
Downloads available in Acrobat PDF format:
- ARD9800 operating manual, edited in the UK - final version, PDF (371kb)
- ARD9800 sales leaflet (91kb)
For government / commercial operators, an encrypted version (ARD9900) is available. It is NOT possible for the ARD9800 to be updated to the ARD9900 encryption specification (for technical, licensing and commercial reasons). The major differences between ARD9800 and ARD9900 are:
* ARD9900 is equipped with the encryption facility.
* ARD9900 is equipped with the ME-1 memory module as standard.
* ARD9900 has a front panel painted in B/W reversed.
Please refer to the ARD9900 page for further information
The ARD9800 was demonstrated at the Dayton and Friedrichshafen shows, Radio Amateurs LOVED IT! The most asked question was, 'When is it available?'.
A review of the new AOR ARD9800 Digital Voice Modem
has been posted to a web site in the USA and contains audio clips too:
http://www.standpipe.com/w2bri/fastmodem/review.htm
The review referred to above makes reference to DSP equipment and switched mode power supplies. In the UK workshop, we have successfully used the ARD9800 with the TenTec Jupiter 538 transceiver (which is an always-on DSP unit), the 963PS switched mode power supply was also used. We note that the ARD9800 is a 'little fussy' about earth loops though when used with a common power unit (running the transceiver and accessories from the same unit).
The 'eham.net' site also has a UK owners review:
M0NKD
Mar 12, 2004 16:19
Rating: 5/5
Prepare yourselves
http://www.eham.net/reviews/review/28911
Chris Lorek is currently carrying out a review for publication in the RSGB RadCom, they have prioritised the publication but we do not know yet (March'04) which issue it will appear in.
ARD9800
LIAISON WEB SITE (for AR9000 too)
An independent web site has been established to enable like-minded
people to compare results and set up transmission schedules (November
2003). Take a look at http://www.hamradio-dv.org
Suggested frequencies are:
-
7.169MHz, 7.170MHz, 7.173MHz, 7.176MHz, 7.290 - 7.299MHz
-
14.236MHz USB (noisy in UK), try 14.255MHz USB
-
18.1625 USB
-
21.370MHz USB
There is an informal NET every Saturday and Sunday at 20:00 UTC on 14.236MHz +/- 3kHz USB
| Modulation method: | OFDM |
| Band width: | 300 Hz - 2500 Hz, 36 carriers |
| Symbol Rate: | 20 mS (50 baud) |
| Guard interval: | 4mS |
| Tone steps: | 62.5 Hz |
| Modulation method: | 36 carriers: DQPSK (3.6K) |
| AFC: | +/- 125 Hz |
| Error correction: | Voice: Golay + Hamming Video/Data: Covolution + Reed-Solomon |
| Header: | 1 Sec. 3 tones + BPSK training pattern for synchronization |
| Digital voice: | AMBE2020 coder, decoder |
| Signal detection: | Automatic Digital detect, Automatic switching between analogue mode and digital mode |
| Video Compression: | AOR original adaptive JPEG |
| Video: | NTSC Input/Output |
| Power requirements: | 10 ~ 16 V DC, Approximately 200 mA Typ(@ 12 V DC) 6 V DC by internal jumper setting |
| Serial port: | RS-232C, 9600 bps, Asynchronous |
| Dimensions (w, h, d): |
100 x 32 x 158 (mm) or 3.94 x 1.26 x 6.14 (inches) (Projections excluded.) |
| Connectors: | Radio: Microphone output (level adjustable) Speaker input (500 mV ~ 5 V p-p), PTT (Push To Talk) Video IN/OUT: NTSC 1 V p-p (75 ohm) |
| MIC: | Microphone input, Speaker output, PTT input |
| Others: | Signal Encryption for commercial applications (where permitted; special commercial version required) Analogue/Digital mode selector Video capture/transmit switch |
Note: Image transfer 'out of the carton box' requires the optional ME-1 memory card but supports NTSC image format only. The ARD9800 hardware is capable of supporting PAL but a small hardware modification involving a crystal change and couple of SMD capacitors is required plus a firmware update... this is carried out free of charge in the UK workshop at the time of purchase.
As the file format transferred over the air is identical for NTSC and PAL, units of different types remain compatible with each other.
Retro-upgrades are available for a small charge, please enquire.
ARD9800 DIGITAL COMMUNICATIONS MODEM FAQ
Q: WHY DO I WANT DIGITAL VOICE COMMUNICATIONS?
A: HF SSB is OK but it has its limitations. The ARD9800 Digital Voice System can dramatically improve your HF communications.
1. The ARD9800 provides NEAR FM QUALITY audio using SSB.
2. The digital signals require LESS SIGNAL than analog throughput making operations possible under adverse band conditions.
Q: MUST I MODIFY MY HF TRANSCEIVER?
A: No! Changes to your rig are not needed. All you have to do is solder the connector to the cable for the mic input to your transceiver. A cable and 8-pin round mic connector are provided with the ARD9800. (Optionally, you may also purchase a pre-made cable for most popular transceivers.) It's basically "plug & play." The ARD9800 system uses digital tones confined to the normal voice audio spectrum. That means your transceiver should pass the digital signals as it would any normal voice communication. When you transmit normal SSB signals, your operations are the same as always. To transmit digital signals, you simply select the digital mode using a front panel switch on the ARD9800.
Q: IS IT DIFFICULT TO CONNECT?
A: No! There are two simple connections to your transceiver.
1. To the mic input jack of your transceiver.
2. From the "speaker out" connection of your transceiver to the "speaker in" jack of the ARD9800. That's it!
3. The only other connection is to a 12VDC power source.
Q: HOW DO I KNOW THE PROPER CONNECTIONS FOR MY RIG'S MIC INPUT?
A: Most transceivers have the pin-outs for their microphone connections shown in their respective operator's manuals. Sometimes they are listed under packet radio connections. You can also check your radio manufacturer's web site or other ham radio web sites. (AOR urges you to be sure the information is accurate before you proceed.)
Q: CAN I STILL USE MY EXISTING MICROPHONE AND EXTERNAL STATION SPEAKER?
A: Yes. You may have to make an adapter for the pin-outs of your mic to match the ARD9800's input, or re-solder the pin connections on your mic's cable, but that's all. The ARD9800 comes with a mic, so you may not want to change your mic at all. The ARD9800 has a "speaker out" jack for use with an external station speaker. Note that the ARD9800 also has an internal speaker and a volume control.
Q: DO I GIVE UP USING MY TRANSCEIVER FOR ANALOGUE COMMUNICATIONS?
A: No! You retain the normal ability to use your transceiver as you have in the past. The ARD9800 adds digital communications to your abilities.
In fact, the ARD9800 lets normal analogue communications pass through, but automatically recognizes digital communications from another ARD9800 unit.
Q: DO I HAVE TO CONSTANTLY ADJUST THE TRANSCEIVER WHILE USING THE ARD9800?
A: No. The ARD9800 uses a protocol that accounts for a reasonable amount of drift during the contact.
Q: SHOULD I WAIT FOR ONE OF THE MANUFACTURERS TO DEVELOP A DIGITAL SYSTEM?
A: The ARD9800 system is here today! Best of all, it can be used with ANY transceiver, so you're not captive to just one manufacturer's digital platform.
Q: DOES IT WORK IN OTHER MODES?
A: Yes! The ARD9800 can be used in AM or FM modes, however, FM mobile operation could be prone to "picket fencing" which might result in the loss of data. Also, repeater "key-up" time could delay the passing of the ARD9800 digital "header" causing a loss of data. As such, AOR cannot make any warranty as to the dependability of the digital mode in every given situation. (Just as any manufacturer cannot warrant what band conditions will be at any given time.)
Q: WILL I HAVE TO OPERATE DIFFERENTLY?
A: Not really. We suggest that "CQ" calls in digital mode be kept short because a "digital header" is sent at the start of each transmission. This header allows other ARD9800 units to "lock on" to the digital transmission. Likewise, we suggest a pause of about 1 second at the beginning of each transmission to allow the header to clear. You might also consider calling "CQ Digital" in the analogue SSB mode. A digital response from another AR9800 user will be automatically recognized by your unit.
Q: CAN I ONLY TALK WITH ONE USER AT A TIME?
A: NO! You can speak with as many similarly-equipped operators as you wish. The ARD9800 uses an FEC protocol that does not require acknowledgement. Therefore, you can communicate "one to one" or in a "round table" just as you do using SSB today.
Q: MUST I SWITCH BETWEEN DIGITAL AND ANALOGUE COMMUNICATIONS?
A: The ARD9800 automatically recognizes digital transmissions from other ARD9800 units.
You can select transmitting in digital or analogue modes using the front panel switch on the ARD9800.
Q: WHAT DO OTHER OPERATORS (NOT EQUIPPED WITH ARD9800) HEAR?
A: Analogue operators will hear the header tones at the beginning of each transmission and then a "buzzing" sound as the digital transmission continues.
Q: WHAT DOES THE DECODED DIGITAL TRANSMISSION SOUND LIKE?
A: It's been described as "near FM" in its quality. It's quite remarkable and one of the big advantages of using the ARD9800.
Q: HOW MUST I IDENTIFY MY STATION?
A: Check the rules that apply in your individual country. In the USA, it is acceptable to identify in the mode you are using, in this case, digital. You may also augment your ID using Morse tones or analogue SSB. In the UK, the callsign must be stated at least every 15 minutes in a conventional mode (SSB/AM/FM).
Q: WHAT ELSE DOES IT DO?
A: With the optional memory board, images can be easily transferred, similar to SSTV but we believe the ARD9800 sends a higher quality image. You can also send file transfers. The ARD9800 has ports for composite video input and output. That means you can easily send an image captured from a video camera or digital camera that has a normal NTSC "video out" jack (PAL version now available - ME1 required). Likewise, you can display and/or save received images on a monitor or storage device that uses a normal composite NTSC video input.
Q: CAN ARD9800 SIGNALS BE ENCRYPTED?
A: NO! That would not be acceptable on the Amateur Radio Bands. The G4GUO protocol is an open, published format that has been adopted for digital voice communications by AOR. It is not a form of encryption and there is no ability to activate encryption in the ARD9800. AOR offers a commercial version called the ARD9900 which is intended for commercial users only on commercial bands. Encryption is a feature available on the ARD9900.
Q: WHAT IS INCLUDED WITH THE ARD9800?
A: You get:
1. ARD9800 Modem unit
2. Power cable for connection to 12 VDC
3. Speaker connection cable (from speaker out on your rig to ARD9800 rear panel)
4. Mic Input cable (from rear panel of ARD9800 to mic input jack of your rig)
5. 8 pin circular mic input connector (requires soldering for your rig's input scheme)
6. Microphone for connection to front of ARD9800
7. Computer cable (from rear of ARD9800 to serial port of your computer)
8. Operator's manual.
Q: ARE THERE ACCESSORIES I CAN PURCHASE FOR THE ARD9800?
A: 1. 12VDC Power cube
2. Memory module VM9800 (needed for sending/receiving images).
3. Pre-made microphone jack input cables for most popular transceivers (ADONIS).
Q: Do I have to modify my transceiver?
A: No. Nearly all transceivers can accommodate the input coming from the ARD9800 directly into the microphone port.
Q: Is it difficult to connect?
A: No. If you have connected an external modem to a computer or a packet terminal node controller to a ham radio, the process is similar. Simple connections are all that is needed.
Q: What do I need to connect?
A: You must build or buy a cable that matches the microphone-input pins on your transceiver. Second, you simply connect the provided cable between your transceiver's "speaker out" port and the "speaker in" port of the ARD9800. Finally, you must connect the ARD9800 to a 12 VDC power source.
As optional enhancements, you can connect an external station speaker to the ARD9800, you may use the provided serial-port interface cable to connect the ARD9800 to your computer and if you have purchased the optional memory expansion module, you can transmit and receive images using the video in/out ports.
Q: How do I set my transceiver for digital operations?
A: Very few changes are needed. You should not use the "Noise Blanker" or have any "Narrow" band pass filters activated. Turn off any Digital Signal Processing (DSP) devices. Turn off the speech processor. After installing the ARD9800, be sure to check your audio output levels (the ALC meter is one method). You may need to adjust your transceiver's mic gain, and/or the output of the ARD9800 to obtain the best setting.
Q: What may I use to provide power to the ARD9800?
A: AOR recommends the use of a 12 VDC regulated power supply or a 12 VDC battery. Try to avoid using "wall cube" supplies or power sources that may have "ripple."
Q: What other tips can you provide?
A: Use quality shielded microphone cable for the connection between the ARD9800 and your transceiver, or buy a "packet" interface cable from your transceiver's manufacturer. Also, Adonis microphone matching cables are an exact match to the pin-outs of the ARD9800 to the microphone inputs of most modern transceivers. Be sure your ARD9800 is well grounded so as to avoid stray RF problems.
Q: My power output meter stays in the same place when I transmit, even though I am using SSB. Is that normal?
A: Yes. The ARD9800 transmits using 36 PSK sub-carriers. The waveform looks almost like an FM signal. As a result, you may be able to transmit and receive extremely high quality digital audio using considerably less output power than that of an analogue SSB conversation. Those who have used PSK31 already know that not much power is necessary for a contact in that mode. If you are concerned about your transceiver's duty cycle, cut the power output.
© Copyright AOR UK LTD 2006. All other trade marks and names
acknowledged. E&OE.