[aprssig] New UZ7HO Soundcard HF (and now VHF) Packet Modem Is Really Hot - update

Stephen H. Smith wa8lmf2 at aol.com
Wed Nov 16 22:41:32 CST 2011

On 11/16/2011 11:37 PM, Stephen H. Smith wrote:
> The new, still in beta, UZ7HO "sound modem" is a sound card application that 
> converts nearly any PC sound card into a high-performance dual-channel 
> 300-baud HF packet modem.   This app emulates the interface of the AGW Packet 
> Engine.  Any program that can work with AGWpe (such as Uiview, APRSpoint, 
> APRSplus or WinAPRS) can instantly use the UZ7HO HF sound modem instead.   
> Unlike AGW, the TNC tone pair used by UZ7HO is tunable, by clicking on a 
> waterfall display like the typical PSK31 app, or by editing the .ini file 
> created on first run..  It has multiple software audio "receivers" running in 
> parallel that tolerate off-frequency tones far better than other HF soft modems.
> The UZ7HO sound modem is evolving so fast it's hard to keep up!
> Late breaking news!!!   As of 16 Nov 2011, version .29 now supports 1200 baud 
> VHF mode as well as 300 baud HF.  With a stereo input sound system, you can 
> now use HF and VHF simultaneously!    I've repacked the Ver .29 beta into a 
> standard Windows "wizard"-type installer that creates the directory, desktop 
> shortcut, and also includes G7OMN's PDF user guide.  Download the package 
> from my website at:
> . <http://wa8lmf.net/miscinfo/UZ7HO-Soundmodem-Install-Ver-.29-Beta.exe>

I just got back from a round trip to Chicago,  and compared the UZ7HO 
soundmodem against my "gold standard" of MixW 2.20 as a HF Packet TNC for 30M 
HF APRS from the mobile on the entire trip.

I actually operated both soft TNCs simultaneously on my Griffin Elecronics  
iMic external USB sound system, described on my website at:


The iMic was coupled to my FT-857 with the home-brew tone-keyed sound card 
interface described on my web site at:

<http://wa8lmf.net/ham/tonekeyer.htm> .

A tone-keyed interface system like this (or the Tigertronics SignaLink) is 
almost essential when using multiple sound apps on the same sound system 
simultaneously, since multiple apps can't share the usual serial port TX PTT 
keying scheme.

Since UIview was "full up" with the TNC port occupied by the link to my Kenwood 
D700 on VHF, and the local server port was in use with the MixW connection, I 
linked the UZ7HO soundmodem to a separate program, APRSpoint, instead.  
APRSpoint (which is effectively a plugin to MS MapPoint) has native support for 
the AGW Packet Engine and also works perfectly with UZ7HO on both RX and TX.

If anyone wants to look up the raw data on APRS.fi, etc, the UIview/MixW setup 
was using WA8LMF-2, while the APRSpoint/UZ7HO setup was beaconing WA8LMF-1.    
Screen caps of both map displays during the trip are here on my website:


I thought Mix was hot as a packet modem, but this new UZ7HO modem absolutely 
blows it away!

My initial impression was that UZ7HO and MixW copied about equally well for 
stations that were EXACTLY on frequency.  For, stations more than 10-20 Hz off 
frequency, UZ7HO copied them successfully about twice as often as MixW.  As the 
afternoon faded into evening, the difference between the two softmodems was 
dramatic.   MixW didn't copy the stations on the west coast, plagued with 
multihop propagation and multipath, at all.   UZ7HO copied them consistently.  
(See the last screen shot on the page linked above.)



Stephen H. Smith    wa8lmf (at) aol.com
Skype:        WA8LMF
Home Page:          http://wa8lmf.net

=====  Vista & Win7 Install Issues for UI-View and Precision Mapping =====

*** HF APRS over PSK63 ***

"APRS 101"  Explanation of APRS Path Selection & Digipeating

More information about the aprssig mailing list