W/resp to antenna pattern measurement techniques, some very important things have been posted here, in fragmented form, from several knowledgeable guys: * You can measure at 0 degrees azimuth, using
it. There are a number of the spectrogram programs that would allow you to accurately measure the amplitude of a signal coming in from the sound card. I don't know that they will log it to a file (w
A technique to disable the AGC that works with many receivers is to advance the AF gain to maximum and reduce the RF Gain untill the S-Meter rises to S9 or more. You can acheive a linear dynamic rang
So would turning off the AGC and digitizing the audio. If anyone finds a program to support the latter, I'd like to know about it. n2ea jimjarvis@ieee.org Hi Jim, I was very surprised to learn today
receivers is to advance S-Meter rises to S9 or 30 db using this It would be much better to just use a step attenuator and set the S meter to the same reading down low on the scale then to depend on
Why not? Presumably the gain of the radio will be stable (in the short run). The sound card gain likewise. The sampling rate of the sound card does change a bit with temperature and time, but it's do
Also, since most receiver AGCs are not linear, they respond to a db of change quicker at some areas of the meter than others. Some experimentation to show at what level the receiver is most sensitive
(in the short the sound card The word "presuming" about sums it all up. It's a HUGE chain of gain stages including everything from RF through IF and audio stages and right up to the A/D conversion.
You can do automated measurements with S-Meter readings if you use the attenuator to calibrate your S-Meter. This will give correct relative spacing between cal points in dB. If a signal source of kn
I'd suspect the short term stability of the MJF attenuators is reasonably good. Most things ARE, for short intervals. The big source of error is likely switches in the attenuator. I agree with Tom, h
This is easy enough to test for. Put the voltmeter or soundcard on the receiver output. Feed the receiver with a steady source like a signal generator, and then use the calibrated step attenuator to
I don't know about that... The linearity can't be all that bad, or you'd have terrible IMD kinds of problems. I wouldn't expect the receiver to have, say, 50-60 dB of instantaneous dynamic range, eit
The approach used in RELEDOP is to use three orthogonal resistively loaded nonresonant dipoles (essentially efield probes) and then using orientation data, convert to horizontal and vertical directio
attenuators attenuator. I don't know how the current switches are, but the pads I have can sit for several months in my dusty shop and never give a moments trouble. The only problem I've had was aft
bad, or you'd Receivers are for the most part acceptable in mixing and distortion to our ears (not to a precision instrument) because they have AGC, and because they limit the number of signals that
Another possible program source for the measurements is at the Degen Designs web page http://www.degendesigns.com/Catalog.htm where they use a Dataq A/D (DI-194RS) http://www.dataq.com/ that costs $2
Somehow, I don't think trying to make precision measurements in among a bunch of other signals would be a good idea. The PSK problem has many sources, I think. I've only just started fooling with PSK