[Ham-Linux] Live or deceased?

[Dr. Gerald N. Johnson]

On 7/4/2013 10:01 AM, Bob McConnell wrote:
> Dr. Gerald N. Johnson wrote:
>> Perhaps we should talk Linux for ham applications. Some time ago I had
>> decent results using puppy linux and FLdigi for HF digital modes. The
>> FT-857's line in and out made for a simple cable not needing isolation
>> transformers and the 857's digital vox kept it very simple.
>>
>> 73, Jerry, K0CQ
>>
>
> I've been thinking about something similar. Most of my computers are
> running Slackware and I have an ICOM 706 buried in the back room. I
> hadn't set it up due to antenna restrictions that have only recently
> been rescinded. I have been keeping track of the fldigi releases as well
> as other similar packages, but haven't had time to play around with
> them. I thought that would change when I retired, but we still haven't
> finished catching up with all the projects that we put on hold while I
> was still working. A lot of our time since has been spent visiting with
> our grandchildren.
>
> The overall plan includes erecting a Shakespeare III whip, hooking up
> the 706 and one of the computers so I can get the receive side working.
> Then I have to take the general exam so I can get busy on HF. In the
> meantime, I have some 2M transceivers and a pair of UDS 202T modems for
> packet and APRS. I'm not sure what I am going to connect them with to
> capture that traffic though.

I know the 202T uses the same tones as 1200 baud packet, but I don't 
recall anyone using those for packet in recent decades. It was so much 
handier to use a TNC with all the ham radio packet details in the 
firmware, my first one was a Heathkit, then later other TNC2 versions. 
In Linux most of the basis of the packet format is in the TCP/IP package 
except that the address field for packet can be much longer and be 
alphanumeric. Longer to accomodate ham calls and digipeaters. I haven't 
been on VHF packet in several years now, I moved and the local activity 
wasn't heavy. The computer side with a TNC is simple, just an ASCII 
serial communications program works, its handy to have one to capture to 
files sometimes. I had one running I wrote, probably in CP/M or MS DOS 
that would monitor weather data on APRS that I ran for years, thinking 
the data might be useful for a weather forecasting client, but I found 
the ham weather stations to be way different from NWS observations even 
on days when conditions should have been uniform over the area. The 
weather station problem was that anemometers were never at the standard 
10m height and away from buildings and trees while the thermometers were 
not shielded from solar heat hitting them directly nor at the standard 
2m height over mowed grass.

Before I moved the main hamshack computer was set up to dual boot MS-DOS 
or Fedora, but I booted it from a CD-ROM to puppy linux for using 
FLDIGI. Today I'm still surrounded by boxes of books and electronics 
parts and my hamshack is very compact, mostly a 17" square stool top 
here in my computer center where I have 4 desktops and a laptop. One 
desktop and laptop run Xp, one desktop runs windoze 98, one runs DOS-5, 
and one dual boots Fedora or OS/2. My work involves software for weather 
in OS/2 mostly though the client increasingly wants Linux versions which 
for me are a whole lot more work. I have a better compiler in OS/2 than 
in Linux and a super debugger that I live and die by. Much of the 
graphic results at www.weather.net as well as many of the text listings 
of weather are done by my software. The animated graphics are created on 
the user demand.

Today sound card software can do all that a TNC did, though I've not 
gathered any for 1200 or 9600 baud packet. I had a dedicated radio for 
9600 baud but the digipeater and bbs may not be on the air anymore.

PSK31 has the best weak signal performance on HF and FLDIGI does that 
well. FLDIGI has many modes, that I've not yet detected on the air. I've 
made PSK31 and RTTY contacts with it.

In VHF AFSK packet modes, audio levels for receive and transmit were the 
greatest difficulties for new users. Being FM with its inherent quieting 
for good S/N and with noise intolerant AFSK detectors, it is important 
to transmit nearly full modulation, not low, but excess for the 
receivers tends to cause distortion and data loss. On receive the TNC 
AFSK detector, most often a PLL needs the best possible audio S/N 
because the PLL is easily kicked out of lock by noise. It helps a great 
deal that the packet radio protocol includes check sums in each packet 
and the receiving side must ACK or REJ each packet and those rejected 
are resent. Too much or too little transmitting and receiving audio 
levels hurts data rates. I've always suggested turning the audio up 
until there are errors, then back it off about 10%.

The rage these days on VHF with a multimode rig are the Joe Taylor modes 
that use multiple tones and very great amounts of forward error 
correction to allow working great distances with moderate power. Like 
EME with a 100 watts and a single long yagi.

My first apartment away from home 50 years ago, I fed the gutter against 
the power wiring ground. It was effective at creating TVI, but would 
have passed all antenna restrictions. Since I moved the last time I'm 
limited by laziness but am working on getting up more antennas. The 
house came with two tripods, one for horizontal TV and one for microwave 
TV. I have 2 and 70cm small yagis on a rotor on the west tripod though 
lately its not been working well, and a dual band gain vertical on the 
other tripod for FM modes. I have a 24' dipole strung between the 
tripods and use it from 40m to 6m with tuners. Its a good antenna for 15 
to 6, but short for 40m but I can make contacts there. I have the space 
for many more, should be out building antennas and supports.

73, Jerry, K0CQ
>
> Bob McConnell
> N2SPP
>