New answers tagged frequency
5
Yes. You're looking for a transverter that will take RF from one source (your radio) and treat it as if it were an IF stage into another system. Here is an example.
Obviously, you'll need to take care that you have operating privileges at the output of the transverter, including making sure spurious emissions are appropriately suppressed, etc.
0
Welcome to ham radio!
Sorry, but there isn't anything practical that you could do to make your Baofeng UV-82 transmit at substantially-higher frequencies.
The obvious answer is of course to buy a radio for the frequency band that you'd like to use. In the US there is a 33 cm ham band from 902 – 928 MHz, and commercial-band radios use similar frequencies.
...
1
You won't be able to, basically you'd have to redesign the whole radio. For example even if you somehow increased the frequency, there would be filters that follow that would cut down the signal. Everything is tuned and matched for a certain frequency range.
There are other options but not for the Baofeng.
0
In SDR receivers which use a mixer in front of the ADC to receive radio spectrum above the ADC sample rate(s), the sample rates and down-conversion frequency are usually independent settable (except possibly for the very bottom end of the range in some SDRs which don’t work (well?) for center frequencies below the sample rate.)
3
This is a consequence of what was discussed in your previous question, that any real-valued function like $\sin(\omega t)$ consists of both positive and negative frequencies.
Multiplying by a complex exponential $e^{i\omega t}$ simply shifts frequency by $\omega$. There are many ways to show this, one way is to simply look it up in a table of Fourier ...
1
A real-valued multiply is the same as an AM modulation, where the result includes both upper and lower sidebands. (Similar to the spectrum of an AM radio station on an SDR waterfall.)
A complex-valued multiply is more like an SSB modulation (plus carrier, depending on modulator depth and offset). So you only get one sideband, upper sideband if the ...
4
That's just the math behind it – everything is alright with these results!
You need to write down the formula of the real-valued $\sin(t)$ in terms of $e^{j2\pi t}$ and $e^{-j2\pi t}$, and you'll see that, as shown in your plots, the real-valued harmonic oscillations have a positive and a negative frequency component – so multiplying two of these yields four ...
1
If I understand your question correctly, the issue is that you have one graph producing a complex output of an FFT and the other producing a floating point output from an FFT.
When you produce an FFT from complex data using a floating point output, you will find that the signal is reflected across the y axis at zero. This is because the floating point ...
0
The output of the FFT you used is complex. When you input a strictly real signal to a FFT that produces a complex result, half of the complex result is the complex conjugate of the other half (this gets rid of all the unwanted imaginary components, when everything is summed up), mirrored.
When you display only the magnitudes in an FFT plot, a complex ...
6
Because mathematically, a function like $\sin(\omega t)$ has an angular frequency of $\omega$ and $-\omega$. Consider:
$$ e^{i\omega t} + e^{-i\omega t} $$
By Euler's formula this can be expanded to:
$$ \cos(\omega t)+i\sin(\omega t) + \cos(-\omega t)+i\sin(-\omega t) $$
By the trig identity $\sin(x) + \sin(-x) = 0$ this simplifies to:
$$ \cos(\omega t)+ \...
3
Gnu Radio doesn't really know anything about frequency in cycles per second (Hz), only cycles per sample. The left of the chart is -0.5 cycles per sample, the middle is 0 cycles per sample, and the right is +0.5 cycles per sample. It's up to you to enter the correct numbers for "bandwidth" and "center frequency" if you want the scale on ...
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