[aprssig] On the Road with PSK63 APRS Mobile -- Day 4

[Chris Moulding]

If you have a 30m PSK31 setup all you need to do is download the APRS 
Messenger program.

The web page is:

http://www.crosscountrywireless.net/aprs_messenger.htm

73,

Chris, G4HYG

Chris Moulding
Cross Country Wireless (2009) Ltd
7 Thirlmere Grove, Bolton, Lancs, BL4 0QB, UK
Tel/fax: +44(0)1204 410626
Mobile:  +44(0)7752 391908
Website: http://www.crosscountrywireless.net
Company number 6780346 registered in England and Wales


On 08/05/10 20:08, Joe Della Barba wrote:
> I have a SSB on my boat set up for PSK31.
> What do I need to do PSK83 APRS?
>
> 73 de N3HGB
>
>
> Joe Della Barba
> joe at dellabarba.com
>
> -----Original Message-----
> From: aprssig-bounces at tapr.org [mailto:aprssig-bounces at tapr.org] On Behalf
> Of Stephen H. Smith
> Sent: Friday, May 07, 2010 2:23 AM
> To: TAPR APRS Mailing List
> Subject: Re: [aprssig] On the Road with PSK63 APRS Mobile -- Day 4
>
> [Posted from Iowa City, IA Motel 6 via WiFi from another motel about 1/3rd
> mile away, using my "WiFi Super Blaster" DX antenna.]
>
> Stephen H. Smith wrote:
>    
>> I'm now on the fourth day of my cross-country trip, experimenting with
>> 30-meters HF  APRS over PSK63.
>>      
> Today I have noticed a number of STRONG   PSK63  signals that simply
> don't decode at all.  These signals appear rather wide, and lack the
> characteristic vertical double-line "railroad track" in the middle of the
> waterfall spectrum display.  They appear to be PSK transmissions with
> excessive TX audio levels (or attempted RF power output), that creates
> intermodulation distortion in the transmitter.
>
> I have just added the paragraphs below to my PSK63 APRS page at:
>
>      <http://wa8lmf.net/APRS_PSK63>
>
> ------------------------------------------------------------------------
>
> IMPORTANT:    PSK63 is a simultaneous two-frequency transmission, unlike
> conventional FSK  packet or RTTY which are single-tone-at-a-time constant
> power transmissions similar to key-down CW.
>
> *It is essential to keep the _average_ output power of the SSB transmitter
> far below maximum in the PSK mode, to avoid severe inter-modulation
> distortion (IMD) of the transmitted signal. *
>
> High IMD will make your signal occupy excessive bandwidth on the air, and
> worse make it unreadable to others, even if the RF level is strong.
> If the transmit level is PROPERLY SET, the PSK63 signal will be received
> without errors, even on signals too weak to move the S-meter.
>
>     1. Disable any speech processors, limiters or compressors in the
>        transmitter audio chain.
>
>     2. If you are reading transmitter output power on an averaging-type
>        wattmeter, you must adjust the soundcard audio level (or
>        transmitter mic gain) for an indicated power of about 1/3rd of the
>        keydown maximum power on CW or FM.  You should NOT be showing any
>        ALC (automatic level control) voltage which would indicate that
>        you are at or trying to exceed maximum transmitter power output.
>
>     3. If you are reading power output on a PEAK reading wattmeter (or
>        monitoring the TX signal on a scope), gradually increase the
>        soundcard output level (or transmitter mic gain) until the power
>        output stops increasing.  Then turn the level back down a bit
>        until the output drops about 20%.  This will ensure that you are
>        not saturating the transmitter power stages.
>
>
> ------------------------------------------------------------------------
>
> --
>
> Stephen H. Smith    wa8lmf (at) aol.com
> EchoLink Node:      WA8LMF  or 14400    [Think bottom of the 2M band]
> Skype:        WA8LMF
> Home Page:          http://wa8lmf.net
>
> NEW!    *** HF APRS over PSK63 ***
>     http://wa8lmf.net/APRS_PSK63/index.htm
>
> Universal HF/VHF/UHF Antenna Mounting System
>    http://wa8lmf.net/mobile/UniversalAntMountSystem.htm
>
> "APRS 101"  Explanation of APRS Path Selection&  Digipeating
>    http://wa8lmf.net/DigiPaths
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>
> _______________________________________________
> aprssig mailing list
> aprssig at tapr.org
> https://www.tapr.org/cgi-bin/mailman/listinfo/aprssig
>
>