Unanswered Questions
102 questions with no upvoted or accepted answers
9
votes
0answers
55 views
How do Radio Regulations and Frequency Allocations Apply to an Ionosonde?
An ionosonde is a special HF radio transmitter that periodically transmits a signal that sweeps across a large portion or the entire HF spectrum to identify the propagation of radio signal in the ...
8
votes
0answers
153 views
UHF FM power amplifier design without expensive software
I'm designing a small UHF data transceiver for the 70cm band, based on a Silicon Labs EZRadioPro Si4463 IC. Modulation is FM, 12.5kHz channel step. The concept is similar to SiLabs' AN656 application ...
6
votes
1answer
64 views
Where to find HF channel models or statistics?
When designing a waveform for packet radio usage, it'd be helpful to know a few things, mainly
distribution of coherency bandwidths
distribution of coherency times
Whilst such statistics are ...
6
votes
0answers
173 views
Beyond Maximum Stable Gain of a transistor
I was plotting constant-gain circles on the Smith chart the other day for a potentially unstable RF transistor.
I recently read on-line that for a potentially unstable transistor the maximum gain ...
6
votes
1answer
621 views
Doppler Shift Compensation in Inter Satellite Communication
I am currently doing a project in the area of optical inter-satellite communication (GEO-LEO).
I am using a optical carrier of 281 THz, and the Doppler shift corresponding to it is ±7 GHz. I ...
5
votes
0answers
73 views
What causes differences in properties of ferrite cores from same material?
Why are the shapes of the impedance curves different for cores made of the same ferrite material?
The impedance (Z) of an inductor wound on a ferrimagnetic core is:
$$Z=j\omega L_s + R_s = j\omega ...
4
votes
0answers
65 views
Commercial Loopstick Antenna Manufacturers
Not sure this is the right forum for this but I thought I'd give it a shot.
I am an electrical engineer working on a product that needs a loopstick antenna.
I had thought that AM radios were so ...
4
votes
0answers
89 views
Dipole loading coil winding directions?
A single inductive loading coil in a vertical or a pair of loading coils in a dipole are commonly used to match a given total antenna length parameter to a given frequency wavelength (where the ratio ...
4
votes
0answers
239 views
ISS APRS Digipeater with Kam XL and ICOM IC-910H
I am trying to use the ISS APRS digipeater which transmits at 437.55MHz.
Hardware setup consists of the following
ICOM IC-910H.
The transceiver has been connected to a Windows PC running a HAM ...
3
votes
1answer
108 views
Are there any “parrot” repeater software projects out there?
I happened across a discussion on building repeaters for Amateur radio, which lead to looking at GMRS repeaters (because apparently this is a potential source for inexpensive 70 cm Amateur repeaters), ...
3
votes
0answers
50 views
9:1 unun material and power loss
I need to build another 9:1 unun and I start searching for my toroids... (I have build 2-3 something like 4 years ago)...
In parallel I checked on Google about the correct toroid etc so I found 2-3 ...
3
votes
0answers
41 views
What value goes in the AX.25 PID field if the Layer 3 protocol is not defined in the standard?
I am working on space-ground networking for a Cube Satellite, and one of our candidate Layer 2 protocols is AX.25. We haven't settled on a physical layer, but it's likely to be some form of quadrature-...
3
votes
0answers
82 views
I/Q demodulation of DSBSC-AM signals
I was looking at some Stereo FM demodulators on the Internet, and I can't understand
the use of the complex to real block for demodulation of the L-R signal (DSBSC-AM)
which can be seen in different ...
3
votes
0answers
45 views
How to simulate two antennas in 4nec2
I need to simulate 2 helix antennae placed side by side, and see the resultant radiation pattern. But after adding the second antenna with a separate and when I try to simulate 4nec2, only simulated ...
3
votes
0answers
79 views
Where did the LP to BP transformation $ \frac{\omega ^{2}-\omega_0^{2}}{\omega\cdot BW} $ come from?
I'm not sure this question is appropriate for this site, but I feel that if anyone knows about a filter, a radio ham knows!
And as a ham myself I feel I need to understand this important area better. ...
