A homemade RF signal generator with these features:
- Frequency range: 5MHz to 2.1GHz
- Amplitude range: approx. -40dbm to +15dbm (slightly frequency dependent)
- Modulation
- AM
- FM
- Up to 12.5MHz frequency deviation
- QAM
- Up to 32 constellation points
- Up to 33M samples per second
- Up to 36 samples per symbol
- Pulse-shaping and differential encoding
- External I/Q inputs
- AC/DC coupling
- Up to +30dbm/10Vpk input
- Up to 10MHz of bandwidth
- Spectral purity@+10dbm:
- Harmonic:
- f >= 150MHz: <-30dbc
- f >= 10MHz: <-25dbc
- f < 10MHz: <-15dbc
- Non-harmonic:
- <-50dbc (limited by noise floor for lower output power)
- Phase noise:
- <-80dbc/Hz@10kHz offset
- Harmonic:
- Gain experience with RF circuit design
- Unwilling to pay the price for commercial generators (of course this one can't compete with a commercial one but should be good enough for simple RF experiments)
For a high level overview see the description of the RF generation. For the effect of RF shielding see these measurements.
The inside: (I reused the frontpanel PCB from this project)
The external modulation input PCB:
The main RF board:
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