ARES - Missouri Emergency Services
2M FM - Less common
application of
DIGITAL
Modes
This same information
may be applied to UHF also.
This page is not meant to be 'all
inclusive' - explore the links throughout the information provided
here.
The only way I'll improve this page is thru feedback, please
let me know via my callsign @ ARRL.NET
Most important is to
experiment and improve our ability to communicate!
|
2M FM simplex |
does it work? |
what frequency do I use? |
Draw backs |
|
Use anything from a 50 watt* mobile to a milliwatt HT. * watch for overheating |
YES ! |
The ARRL
Band Plan: |
Unlike HF SSB, 2M FM will occupy an entire 'channel' (at least 5 KHz) In other words only one conversation may be on each frequency. On 20M HF SSB there are often 10+ conversations going... If used on voice simplex you will "hear from" other HAMs who do not share your enthusiasm for the Digital modes !!! |
Computer to Radio
interfacing:
Many interfaces/software require a Sound Blaster
'compatible' sound card. Overall it is best to go with what the local
HAMs (your area) are
using. My interface is a RASCAL unit from K4ABT
(http://www.packetradio.com/psk31.htm
), however there are LOTS of
excellent units available. One thing to consider is the ability to
'plug into' more than one radio, if your radio(s) use the mini Din 6
pin plug then the work is easier. Both my Yaesu FT 817 (QRP HF/V/U)
and ICOM IC 207 (dual band mobile) use the same connection.
RECEIVE ONLY:
All
that is required is a cable from the radio's speaker jack to the MIC
input for the soundcard on the computer. I have used a Radio Shack
cable PN 42-2444 or PN 42-2497 for this purpose. Just run the Digital
software of your choice. Be sure to keep the volume LOW, 1/4 up is
plenty. *These
directions do assume you will be using a fairly 'modern' radio, older
equipment may differ.
Software: (there
are a LOT more good choices)
DigiPan http://www.digipan.net/ the 'old standby' for PSK 31.
Stream http://www.qsl.net/zl1bpu/MFSK/software/ MFSK mode with FEC, excellent for weak signal work.
MT63 http://iz8bly.sysonline.it/MT63/index.htm this is a FAST mode, but also wide in bandwidth.
MixW http://www.mixw.net/ not freeware, but a comprehensive package.
SSTV http://www.qsl.net/mmhamsoft/mmsstv/index.htm MMSSTV is an excellent way to send pictures. Calibrate before using - instructions found at http://ca.geocities.com/antennas/ .
Data transfer
speed: (These times are 'relative' to my
installation - your results may vary. But it does give a
general idea of speed.)
|
MODE |
XFER Time M:SS |
NOTES: |
|
PSK 31 |
4:24 |
The most popular mode for Digital communication. Unless you are sending considerable text from a file this mode works well. |
|
PSK 63 |
2:11 |
Twice the speed of PSK 31, available in DigiPan and MixW. Very useful for 'faster' file transfer. Fairly good for weak signal use. |
|
MFSK |
3:49 |
Excellent for weak signal work. Uses FEC (forward error correction) which will keep errors at a minimum. Use this mode when the message must be understood. |
|
MT 63 (1 K mode) |
2:09 |
Another good choice for weak signal use, also uses FEC. On HF it does use excess bandwidth. (uses 500-1500 Hz) |
|
MT 63 (2 K mode) |
1:05 |
Same as MT 63-1K but even wider. Best suited for VHF/UHF use. (500-2500 Hz) |
|
RTTY |
4:13 |
Another popular mode, however it is not well suited for copy/paste between Windows programs. Some character fomatting may be lost. |
73 & GL - hope to 'see' you on the Waterfall!
Larry
KB0EMB
Independence RACES
Jackson Co
ARES
MO ARES - MESDN
Last update – 10/03/2003