FCC Denies RM-11392

Don't many of the PMBOs now require P3 for connections, and will refuse P1/P2 connection requests? That's the primary reason I can think of...

 

Actually, the SCS modem is a true bargain at less than a thousand dollars. It offers performance that is comparable to HF modems that sold for tens of thousands a few years ago. It compares quite favorably with the current state-of-the-art for HF modems -- at a cost that is less than 20% of the "inexpensive" versions.

HF modem performance has room for improvement. With a few "tweaks" to the protocol, better throughputs are possible with current modem signaling.

The KAM are not used in normal operation because they are so slow that a channel is occupied for a long period of time. PACTOR 1 operation is enabled only during emergencies, when additional EMCOMM-only PMBO are activated.

 

Ok lets put it this way. You are using winlink to send email from an amateur to a non-amateur. That is bypassing a service that is available. Using APRS is ham to ham and therefore the rule about regular use does not apply. What we have been talking about here is ham radio becoming a common carrier service for hams to access a commercial service. Not hams talking to other hams using the amateur radio bands.

Now about you being banned from the HHH net you must be a lid because they don't ban many people on that net. In fact you are the first one I have heard about being banned. I guess you just cannot follow net protocol or you just have a beef with them. If your operating habits got you kicked off a very friendly net then you must have some bad operating skills.

 

Show me where I have misspelled a word on my posts? I may not spell that great but I do know how to use technology to it's fullest. Spell check is the greatest invention ever and wonder why some of you don't use it.

 

Exactly right. You cannot use a KAM to connect to any of them. Try connecting to WB5TAX sometime. He only accepts PIII connects and if you try to use a KAM to connect it will give you a short message telling you that. So much for making a system backward compatible. If the system will connect just long enough for it to tell you that your connection is not allowed then why not just let it transfer in the first place. All this does is force folks to buy SCS modems and that is why I believe that Steve Waterman and crew get kickbacks from SCS for every modem sold.

 

They might be slow Larry but they take up less bandwidth than a PIII connect. Plus the fact that most of you winlids are passing attachments I have seen PIII sessions last for over an hour many times. To me that is a waste of not only bandwidth but time. In that bandwidth that a PIII signal takes you could have 5 P1 connections going on. Also take in the fact that all PMBO's start out in P1 and then without warning and without checking the adjacent frequencies it expands from 500hz to 2.7khz without warning.

This is the reason why this petition was done in the first place. Limiting it to 1.5khz would not affect the use of your SCS modem that much. You guys seem to think it would have effectively banned it's use but it did not do that. You guys seem to see only what you want to see and be damned anything else.

 

First of all, all Winlink users are limited to 30 minutes in a 24 hour period, so the "over an hour" claim is false.

Second, the maximum occupied bandwidth of a P-III signal is 2140 Hz -- 560 Hz less than your statement. Again, false information in your statement.

Third, one wonders why you insist upon operating (apparently exclusively) on frequencies known to be inhabited by a PMBO. There are VERY few PMBO, and a VERY limited segment in which they may operate. This is akin to walking in the middle of a traffic lane and complaining about the cars that "encroach" on "your" space. The PMBO cannot leave their very tiny allowed segment.

Finally, the spectral efficiency of P-III is many times that of P-I, PSK31, PSK63, HF Packet, and SITOR / AMTOR. At SL6, SL5, and SL4 the P-III modem occupies 0.593 to 0.594 Hz per bit per second. PSK31 and PSK63 occupy 2 Hz per bit per second. SITOR / AMTOR occupies 2.545.

Only when forced to fall back to SL2 does the spectral efficiency fall to above 2 Hz per bit per second. (2.367)

That fallback comes at the cost of a DECREASE by a factor of SIX in rate (from 3600bps to 600 bps), and an INCREASE by a factor of SIX in bandwidth (from 0.594 to 2.367Hz per bit per second). The actual available throughput (compressed ASCII) falls from around 5000 bps to around 300 bps -- a DECREASE by a factor of at least 16.

As an engineer and modem designer, I look at simple technical facts to form an opinion of any design -- whether hardware or software. All modem designers of HF modems must assume that the modem will be used with EXISTING radios, with EXISTING filter characteristics. The universal "standard" for bandwidth is the width of a "normal" SSB voice signal that passed through the common filter bandpass of 2500 Hz or less.

Because the 2500 Hz points are down by -3 dB or more on the filter slopes of some radios, we look for the "sweet spot" that can be passed by ALL radios. That is generally agreed to be around 2200 Hz. Just about any SSB radio made since 1960 or so can be successfully used with a modem that has a 2.2 kHz signal bandwidth.

I once successfully used a 1960's vintage Russian 400 Watt transmitter mounted in a Russian communications trailer to set up a full-duplex (~1 MHz separation) HF digital voice link in the Sahara Desert. I also successfully tested with Kenwood 440, Kenwood TS-520, Icom 735, and Icom 725 -- among other radios.