Goal is to determine short term fluctuations in effective optical path from WWV and other beacons (NYC) through ionosphere.
One method is to measure phase fluctuations of a CW carrier on short time scales. This can be done with an SDR that is tuned near zero beat, so that lower mixing product phase reflects carrier phase.
GPS-disciplined receiver can be used to determine stability of local oscillator in SDR.
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CO to MA propagation estimates:
Signals:
ISM bands: , can broadcast 1 W!
WWV: Minuts 8 from WWV and minute 48 from WWVH send out ionosphere diagnostic signals. See https://www.nist.gov/pml/time-and-frequency-division/time-services/wwvwwvh-scientific-modulation-working-group
These each last 45 seconds.
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Transmitter RWM in Moscow transmits a CW waveform for around 8 minutes on the half hour, at frequencies that are close to WWV, namely (see https://en.wikipedia.org/wiki/RWM) 4.996 MHz with 5 kW and on 9.996 and 14.996 MHz with 8 kW
So at 15 MHz that's a wavelength of 20m. Should be workable at 2000 UT which is afternoon (4 to 5 pm). VOCAP above is for 8 kW transmit power.
Web SDrs
MA http://sigmasdr.ddns.net:8073/
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| item | part number | vendor | price | notes | references | status |
|---|---|---|---|---|---|---|
| magnetic loop antenna | DXE-RF-PRO-1B | DX engineering | 675 | have one, need one | ordered 8/3/2023 Order #4433160 | |
preamp | DXE-RPA-2 | 250 ea | BNC 12-18 V dc power at 150 mA | dxe-rpa-2.pdf | ordered | |
linear DC power supply for preamps | Tekpower TP3005T Variable Linear DC Power Supply, 0-30V @ 0-5A | amazon.com | 80 | provides clean regulated power to preamps | ordered | |
| delay line for phase slip | DB64 | SRS | 695 | BNC | asked Helen on Aug 3 | |
| 50 ohm signal combiner | ZMSC-2-6+ | minicircuits | 74 | BNC | ZMSC-2-2.pdf | ordered 8/3/2023 Fed Ex ground order # M189BDEC83C0. |
| low pass 30 MHz | BLP-30+ | minicircuits | 50 | BNC place this after the preamp | ordered 8/3/2023 Fed Ex ground | |
| high pass at 2.6MHz | amazon | SMA, note there will be phase slips at WWV freq of 2.5MHz if this is used. Place it between antenna and preamp | https://www.amazon.com/gp/product/B01N9SHS7P/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1 | |||
| SDR radio | Airspy HF+ Discovery | Airspy | 184 | SMA | ordered 8/3/2023 | |
| GPS-disciplined osc. | GPSCSG V2.0 GPS Disciplined Oscillator GPSDO GPS Signal Generator Dual Output | ebay | 112 | SMA Adjustable frequency: 10KHz-220MHz - Frequency accuracy: ±0.2Hz - Output level: 12dBm±2dB (can be customized to any value from -10dBm to 10dBm; amplitude can be calibrated) - Frequency synthesizer crystal oscillator: TCXO - Phase noise: -132dBc at 10KHz - Output type: square wave - Harmonic rejection: even harmonics are better than -50dBc and odd harmonics are better than -10dBc Do we need a low pass filter on this? If so needs SMA connectors | can't find an online manual | ordered 8/1/2023 for mid-Aug delivery |
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