I am supprized to see that my mode-uv work for the P3e
is still remembered :o) I wonder what happened with
the mode-uv transponders designed by the other (New
ealand, Russian, German and ??) groups ? Lately I only
read about the SDX work of NA, UK and DL, but what
about the other parts made by other (none NA,UK,DL)
>From the messages I feel that the SDX seems to be the
best radio at all, with a larger dynamic range, better
aligator killer, better HELAPS etc...
SDR technology is very interresting and it should be
explored, but somehow I feel that only its advantages
are named. So I like to "flip the count" to its other
side to have "the pair of scales in balance".
About the dynamic range, I wonder how it can be better
than an analog receiver. I suppose the RX side (UHF)
will not directly be digitalized (it would need an
high speed and high power ADC) so there is still an
amplifier and down-mixer needed in front. Then there
is only the IF part where it can be dynamically be
better. I guess with analogue electronics this can
also be done :o)
I also seen someone mentioned about 1970 electronics,
as if todays electronics is only better in IC form.
Todays 2007 transistors are much better than in 1970,
they are much smaller, and have a better performance.
Even analogue style transponders can be made better
and smaller size than those in Ao-10, with todays
transistors. Have a look at my modern analogue
transponder system at: http://www.observations.biz
When talking about old technology then HELAPS (or
officially called EE&R) is even more older, from 1952
That the HELAPS works better only due to the "modern"
SDR system is not compairing in a fair way. Then you
compair 2007 SDR electronics with 1975 transistor
electronics. I believe with todays modern discrete
electronics the HELAPS system will work equally or
The SDR system with zero-IF is a nice system which is
very flexible. However zero-IF can have problems with
DC-drift over time what gives unefficient ADC use or
even ADC clipping. It is also more sensitive for low
frequency 1/f noise, and the high frequency digital
processing signals are a serious threat on sensitive
receiver inputs... (also a problems in modern
A Near-Zero-IF system might be a solution but is more
complex to integrate.
The filters at such low frequencies (zero-IF) can be
made very sharp, but the same trick can be done in
analogue way, with an RC low pass filter :o) Several
years ago I present such a bread-bord system as
"Quadrature transponder" where I could easily change
the transponders bandwidth and change from inverted to
none-inverted :o) The difference is that it takes far
less power than a DSP does, and it was extreemly
I agree that digital DSPs are more flexible which is
good when you like to use the same radio for other
This was my vote for the analog transponder systems
I hope the digital SDX works well and hope that its
analog sister will also have a chance to do its work
and gets its technical respect...
73 de William
Be a PS3 game guru.
Get your game face on with the latest PS3 news and previews at Yahoo! Games.
I am thinking of buying a masthead pre-amp for use with the Icom IC-910H
for both satellite and terrestrial work.
There are the AG-25/35 units from Icom which are specially designed
for use with the 910. But I have seen the SSB Electronics units on the
web (SSB-SP-2000/7000) and also the Microset units (PR-145A/430A) and
wonder if these devices perform better than the Icom units. Also, would
the SSB/Microset units require a sequencer.
I would be interested to hear from anyone who has been down this road
with an IC-910H.
Thanks in advance, 73 Martin M0ADY.
Martin Grundy (M0ADY) <m0ady(a)m0ady.org.uk>
RAFT's packet-to-voice circuit only works in the dark, and in a
few days, RAFT will begin entering the late evening time frame
when Northern Hemisphere stations can again use it.
RAFT is nearing its mission life time half-way point. It has
decayed down to 180 nm and will re-enter before the middle of
Due to its low orbit and small footprint, we need command
stations in the Southern USA between Arizona to Georgia to help
us conduct our primary mission of detecting the 218.98 MHz radar
fence when it flies through it. We need command stations in
those states because they are near the radar fence and will be
in the footprint of the radar. The ideal command station has
1) A reasonable 2m beam for ops on 145.825
2) A packet TNC
3) A familiarity with dumb-terminal TNC operations such as
A. Connections, Converse, UNPROTO, etc
B. Remote sysop logon of Kantronics TNC's
4) Desireable, is some experience with UI packets and APRS
The objective of these southern command stations is to logon,
send the command to activate the RAFT Radar receiver for 1
minute in anticipation of passing through the fence. Then
hopefully recording any audio heard on the downlink (145.825).
Of course, once the radar receiver is on, everyone in the
footprint should be able to hear it.
For info, see the ANDE-RAFT operations page:
And for more info on the 216.98 MHz radar receiver, follow the
links to the RAFT design pages.
If you meet the criterial above, lemme know.
US Naval Academy Satellite Lab
I'm looking to find an AZ rotor unit for my station. I found a EL rotor and control box, but need the AZ rotor. Any around?
AMSAT area coordinator, Toledo, Oh.
AMSAT area coordinator, Streator, IL.
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Greetings from Pat N2OEQ
Just a short note to clarify my comment that the older AO-7 technology is reliable after so many years not because the computer and batteries failed, but because the transponders still operate. I love those big old resistors Hi Hi.
I have for sale a Yaesu FT8900R Quadband
(10m/6m/2m/70cm) FM rig in very good condition. Does
50 watts on 10-2m and 35 watts on 70cm. It does dual
receive, so it works great on the satellites, and will
do crossband repeat so you can work 10m or 6m using an
HT around the house. The 8900 comes with the mic,
power cord, manual, and original box. I am asking
$340 shipped in the US.
73s John W5TD
Don't pick lemons.
See all the new 2007 cars at Yahoo! Autos.
Greetings from pat n2oeq
I have been looking forward to the launch of P3E which I thought was going to be this year.
I am concerned about the germans use of the SDR technology over william Liejanier's transponder design.
I am of the belief that signal processing presents a loss in the path, please correct me if I'm wrong.
Williams Hamsat transponder is excellant and made me very interested in P3E.
Besides making the voice unnatural, are other modes allowed through the SDR transponder?
Does the Helaps system compensate for the loss?
I'm of the Keep it simple discipline as once its up there nothing can be done to fix it.
If amsat-dl is monitoring , please update your website and provide a direct Paypal donation utility.
Thanks to amsat-na for the donation to P3E recently. 73, pat
A launch delay has been announced. Details to follow when decisions are made.
TNX es 73 de Ralph Wallio, WØRPK
Hubbert's Peak - The Mother of all Perfect Storms