notes-sdr.txt

Antenna Length:
	1/4th length [in m] = 74948114.5 / f [frequency in Hz]
	1/4th length [in cm] = 7494.81145 / f [frequency in MHz]


Radio Frequency Spectrum Ranges:
	VLF: 3kHz-30kHz   100Km-10Km
	LF:  30kHz-300kHz 10Km-1Km
	MF:  300kHz-3MHz  1Km-100m
	HF:  3MHz-30MHz   100m-10m
	VHF: 30MHz-300MHz 10m-1m
	UHF: 300MHz-3GHz  1m-10cm  L (1-2GHz), S (2-4GHz) band
	SHF: 3GHz-30GHz   10cm-1cm S (2-4GHz), C (4-8GHz), X (8-12GHz), Ku (12-18GHz),
	     K (18-27GHz), Ka (27-40GHz) bands
	EHF: 30GHz-300GHz 1cm-1mm  Ka (27-40GHz), V (40-75GHz), W (75-110GHz),
	     mm (110-300GHz) bands
	* Microwave: 1GHz+
	* Millimeterwave: 30GHz+
	* Long Wave: 148.5-283.5kHz?
	* Medium Wave: 525kHz-1,705kHz (10kHz spacing)
	* Short Wave: 1.6-30MHz
	* FM: 88MHz-108MHz


Usage:
	•	ADS-B (Automatic Dependent Surveillance - Broadcast)
		1,090MHz
		978Mhz (for aircraft exclusively below 18,000'/5,486m in USA)
	•	AIS (Automatic Identification System): 161.975MHz & 162.025MHz
	•	CB radio: around 27MHz
	•	IRNSS/NavIC:	L5 (1,176.45MHz) and S band (2,492.028MHz)
	•	GPS:	L1 (1,575.42MHz), L2 (1,227.60MHz)
	•	GLONASS:	L1 (1,602+[9/16]MHz), L2 (1,246+[7/16]MHz)
	•	HAM/amateur band: 144-14MHz Narrow FM
	•	Marine emergency communication: 2,182kHz
	•	VHF universal use:
		50-54MHz: Amateur Radio 6m band
		108-1,18MHz: Air navigation beacons VOR and Instrument Landing System
		             localizer
		118-1,37MHz: ATC (AM), 121.5MHz is emergency frequency (HF/UHF)
		144-1,48MHz: Amateur Radio 2m band.
	•	Weather Satellites
		Meteor M1: EOL
		Meteor M2: 137.9MHz
		NOAA 15: 137.62MHz
		NOAA 18: 137.9125MHz
		NOAA 19: 137.1MHz


Convert dBi to dBd
	Subtract 2.15 from dBi rating to get equivalent dBd rating.
	*	'i' means it is a measurement relative to an isotropic antenna and 'd'
	means it is a measurement relative to a dipole antenna. Dipoles have a 2.15dB
	gain compared to an isotropic antenna.


Devices:
	• Elonics E4000:
		52-2200MHz (gap approx 1100-1250MHz)
		Approx 50MHz-2.3GHz (possible when used out-of-spec, with gap)
	• NooElec NESDR SMArt
		RTL2832U interface IC
		R820T2 tuner IC
		0.5PPM TCXO
		25MHz-1750MHz
		2.4MHz bandwidth
		Female SMA
	• RTL-SDR Blog v3
		RTL2832U interface IC
		R820T2 tuner IC
		1PPM TCXO
		Bias-tee
		500kHz-1,766MHz (500kHz-24MHz in direct sampling mode)
		2.4MHz bandwidth
		Female SMA