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critical path
Michael Hirsch edited this page Nov 14, 2016
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4 revisions
This page is about the leftmost items on the critical path, that are holding up other parts of development.
- This GNURadio PSK example is set to transmit and receive a binary image of a kitten over a simulated transmitter and receiver.
- The PSK_red-pitaya.grc transmits/receives "on the air", setting a center transmit and receive frequency (say, 3.7 MHz or 50 MHz).
- Using a short hookup wire (or SMA-SMA jumper) from RX1 to TX1 of the Red Pitaya and setting transmit amplitude to 0.01 is a loopback test
- To confirm RF is actually being used, you can connect an external oscilloscope to the wire and watch the waveform stream by.
Absolute timing reference is vital to measuring radar pulses--multistatic radar measures by absolute time delay
- has anyone (Pavel, NJIT, Haystack, et al) come up with a 1 PPS triggered transmit sequence?
- if not, how long till it's ready?
- if not coming soon, consider using DPST PIN diode (or reuse DPDT loopback) transmit switch via GPIO and repeat the transmit waveform once, making the PIN switch cut on/off with precise absolute time.
- with a 1.5 meter length of wire to the RX1 and TX1 connectors, lying on the bench in parallel separated by 6 inches, how much transmit amplitude (0..1) at 50 MHz till receiver overloads?
- what parallel wire seperation is needed to allow full transmit power without receiver overload?
- same as #2, with perpendicular antenna wires.
Raspberry Pi PWM PLL could transmit useful waveforms, but some work was needed to cleanup timing glitches. It wasn't clear if the Raspberry Pi waveform timing glitch fix would be simple, since the issue may have been due to the non-deterministic operating system.
The Red Pitaya came to market October 2016, offering overall cheaper price than Raspberry Pi 3-based system with much better performance from Red Pitaya.