[aprssig] New UZ7HO Soundcard HF Packet Modem Is Really Hot!
Stephen H. Smith
wa8lmf2 at aol.com
Wed Nov 16 03:08:22 CST 2011
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 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. It has multiple software
audio "receivers" running in parallel that tolerate off-frequency tones far
better than other HF soft modems.
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
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.)
Having a fully-functional AGW-compatible soft modem raises some very
interesting possibilities. If you use AGWpe as a soft TNC on VHF, you can
shut down AGW and startup UZ7HO. You then instantly have a 300 baud HF
capability with no hardware changes at all. This will be fantastic for
"DC-to-light" HF/VHF/UHF all-mode radios like Icom 706s, TS-2000s, FT-857s, etc.
Stephen H. Smith wa8lmf (at) aol.com
Home Page: http://wa8lmf.net
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