Charleston: Tower bridge
| Digital TV standard protocols | DVB-S protocol (converts signal to white noise prior to transmission) example spectrum | functional block diagram |
| Intelsat | Satellite coverage maps including IA-8 at longitude 89 West with 52.8dBW EIRP in Ka band and 47.9dBW in Ku band | digital TV signals useful for broadband (400MHz) holography |
| Lyngsat satellite information page | DISH network on EchoStar 8/10 at 110 deg West longitude at 12.2 GHz | |
| NASA satellite tracker | J-Track 3-D database of 300 satellites | |
| PanAmSat | recently acquired by Intelsat | |
| SatcoSX | including AMC5 at 79 West (42dBW EIRP); AMC9 (46dBW EIRP) |
| Analog Devices | AD8347 0.8 GHz to 2.7 GHz Direct Conversion Quadrature Demodulator (with evaluation board available) | local PDF |
| Invacom | QPH 031 Quad polar LNB ($69) | no external reference; hacked with an 11.25 GHz external LO by R. Kimberk; stable to < 0.1 degrees rms on minute time scale |
| VSAT PLL LNB SPV-55SM, 65SM, 75SM with external reference | flange mount, no horn | |
| Multiplier comparison: Gilbert cell vs. diode | Heterodyne spectrometers with very wide bandwidths (Andy Harris 2002, SPIE) | |
| Comparison of Analog Continuum Correlators (Koistinen et al. 2002, IEEE) | ||
| Merrimac Industries | Intro to I & Q modulators (10MHz to 8GHz) | |
| SPC Electronics Corp. | LNB (Low Noise Blockdown Converter) for Ku-Band |
Advantanges of a broadband system over a beacon
| 1. Total power from beacons are weaker: 1-20 dBW EIRP (equivalent isotropic radiated power) rather than 40-50 dBW in the datastream. (Not intended to be picked up by the consumer, some are used for tracking by the service provider. Some are modulated and used for communications.) For comparison, the total power in the SMA 232 GHz beacon on Subaru is about 100nW. If it was isotropic and placed at geostationary altitude (35786km), it would then be 36237km distance from SMA antennas (rather than 200m) and would need to be 3.28 kW = 35 dBW EIRP to provide an equivalent signal (ignoring atmospheric attenuation). In fact, the FWHM of the beacon horn is 9 degree at 232 GHz, which is a gain of 364 = 25.6dB. Thus the EIRP would need to be 60 dBW! |
| 2. Beacon system requires a narrow passband filter (of order 5kHz). For example, the satellite used by the SAO phase monitor drifted out every 30 minutes and computer had to reacquire it via GPIB bus. |
| 3. Beacon system requires downconversion stage from the LNB output (~1 GHz) down to vector voltmeter range (often 500MHz or less). Also, the passband filter is easier to implement at lower frequencies, such as 21 MHz. |
| 4. Beacon system has multiple reflections/standing waves. The broadband system will help wash those out. They manifest themselves in the data as follows: 1) in total power focus scans of the subreflector, one sees oscillations rather than a smooth peak. 2) in the aperture domain, one sees broad radial oscillations (2 or 3 across the dish) in the aperture phase which flip up/down after the subreflector is moved and a new map is made. |
Issues Common to Both Systems:
