3309RE: [V4Protocol] Re: New experimental mode HAM4 and Chat host program for robust keyboard mode..
- Jul 11, 2013
Is to my understanding the H4 ARQ does not work? You can only run FEC FD mode only? Because that’s the only mode I can grt to work in this new release? If I try to call CQ or put in a call into H4 ARQ It’s just sets there and does nothing?
QRV Rick Kd4jrx FM14ab
I think there is a major bug when I built the last Chat and H4FSK TNC run…I will try and look at it today and tomorrow.
I have forwarded info to Finnish EmComm ("TURVA") members & others on HF digi modes in OH.
I will load chat protocol soon and ready for beta testing
73 "Yussi" OH7TE
--- In V4Protocol@yahoogroups.com, dk3cw@... wrote:
> Thanks for improving the V4-Chat protocol, Rick.
> I've forwarded the new file to some EmComm and digital modes interested hams in Germany. As we did before, when V4Chat was released, we'll test and compare the new protocol with the old on. Expect some Bug reports and suggestion for improvements soon.
> vy 73 de Jakob DK3CW
> EmComm liaison officer Frankfurt / Main
> When All Else Fails, Ham Radio Works
> -----UrsprÃ¼ngliche Nachricht-----
> Von: "kn6kb" [rmuething@...]
> Gesendet: Mi. 10.07.2013 20:37
> An: V4Protocol@yahoogroups.com
> Betreff: [V4Protocol] New experimental mode HAM4 and Chat host program for robust keyboard mode..
> Â Initial Alpha release of Chat 0.1.0.1
> Chat and its' companion virtual TNC H4FSK TNC are designed for keyboard operation over HF. This is alpha code â€¦.not well tested or documented yet but appears to be functional. If you are not an experimenter or get frustrated debugging software please wait a few weeks at least until the basic bugs have been worked out.
> Chat and the H4FSK TNC are an outgrowth of the V4 Chat and V4 Protocol released in 2010. I hope this (after initial debugging) will eliminate some of the limitations of V4 and prove to be a reliable keyboard FEC and ARQ mode. Here are the basic features and goals of the program and the Protocol:
> The protocol is called HAM4 short for HAMming Encoded 4 FSK. It uses the same modulation type as V4 (4FSK @ 46.875 baud) and the same bandwidth (200 Hz at -26 dB. However there are several changes that should make the HAM4 Protocol better especially for keyboard operations.
> 1) Lower latency. The HAM4 FEC is included in each character (currently using a Hamming 11, 4 code shortened to 8,4 with a minimum distance of 3). A character consists of 6 4FSK symbols (12 bits) of which 8 are user or code bits. A character time is 128 ms. This translates to a very small latency in the range of 300 ms (the delay from sending the text from the keyboard until it prints to the remote stations screen). This is even lower than modes like PSK-31.
> 2) Strong FEC. The shortened 8,4 code is soft decoded using a lookup table mechanism that computes the distance to the "closest" character. This gives approximately 2 dB additional coding gain (equivalent of increasing the power by about 60%). The soft decoding also allows plotting the received signal quality as each character is received. The soft block encoding on a character by character basis reduces sensitivity to burst errors.
> 3) Full support for ASCII(7bit), extended ASCII(Latin-1), and UTF-8 (Unicode) character sets. This allows full support for most common languages and symbols.
> 4) Fast and continuous tuning and sync tracking. The sync character (also 128 ms) is sent every 1.024 seconds. This non printing character allows fast and accurate DSP tuning to about .5 Hz accuracy and tracking of drifting or off frequency signals. Loss of sync can usually be recovered in 1 to 2 seconds.
> 5) Good FEC and ARQ (Future) throughput. Nominal FEC throughput is approximately 6.8 eight bit characters per second or 68 words per minute.
> 6) Future full binary ARQ capability with approximately 250 bytes/minute ARQ rate.
> If you are familiar with V4 Chat and the V4 protocol this should be easy to pick up. There is basic help but it needs refinement and expansion. Your feedback and comments are appreciated. Good luck and enjoy.
> Rick Muething, KN6KB rmuething@... KN6KB@...
> -----UrsprÃ¼ngliche Nachricht Ende-----
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