Information on TV tuner modules is useful to those working on low cost spectrum analyzers, software defined radios, and other projects. Datasheets on tuner modules are rare. Sometimes you can get the datasheets on the chips used, which is particularly useful to get I2C programming info. Also, you can purchase service schematics for many consumer devices that will at least have the pinout and opening the can may reveal the chips used. Sometimes the PCBs in consumer electronics are marked with the pin designations. Linux drivers have information on I2C programming for various tuner chips.
It is also very hard to find tuner modules for sale. For one time project use, a tuner can be scavanged from a CECB or a dead piece of consumer gear or a cheap PC tuner. Cheap tuner cards can be purchased in case quantities from global sources direct or in single quantities from tiger direct or ebay. NTSC tuner modules are likely to be discontinued.
Older tuner modules used a user supplied analog voltage, which was applied to the tuning diode to control the variable frequency oscillator (VFO). This has largely been replaced with I2C controlled tuners though these still use analog voltages to control AGC on some models. Some spectrum analyzer projects foolishly still use analog voltage tuned tuners or even modify an I2C tuner to apply an external analog voltage. This leads to poorly calibrated spectrum analyzers and unnecessary circuitry. A legitimate reason to do this would be to improve the tuning resolution by using an external PLL. One project added a mixer and a direct digital frequency synthesizer to allow fine tuning.
Many tuners now claim to be "Half-NIM".
NIM and Half-NIM are standard form factors for TV tuner modules. A common form factor simplifies making TVs, DVRs, DVD recorders, VCRs, PC TV tuner cards, and set top boxes which can be customized for different markets by swapping the tuner module as well as making it easier to second source tuners from different manufacturers. Described as "A popular form factor often used in the Chinese DVB-S Market" Maxim Application Note 4178. Size is approximately 40mm by 51mm. Both vertical and horizontal mounting versions have been seen.
Before standardization, tuner module manufacturers did their own thing and tuners were not interchangable. After "standardization", tuner module manufacturers still seem to do their own thing and interchangability doesn't seem to have improved much. The can size, pin spacing, number of pins, varies among different units advertised as Half-NIM. Tuner chips are controlled via I2C. Some tuners require an analog AGC control voltage but in others the AGC can be controlled via I2C. Some require a 33V low current supply for the tuning diode but others have a built in DC-DC converter to make this voltage. Some tuners use 5V, some 3.3V, some a mix of the two.
English language documentation on NIM/Half-NIM is hard to find.
Output formats vary. Some produce an IF frequency, such as 44Mhz. Some produce baseband output. And some produce I/Q quadrature outputs; this is similar to a baseband output but with phase information as well. TV decoder chips expect a specific format which varies based on the decoding scheme used.
Pinouts of Half-NIM tuners do not seem to be well standardized.
Half-NIM
LG: 16 pins on 2.5mm centers in two separated groups. Can size 33.9mm x 58.30mm x 13.9mm.
First number is uniformly numbered pins , second is LG Pin number, third is Sanyo
The sanyo UBA00AL has a similar pinout, however it inserts a pin before pin 7. It uses the TI SN76168 and Toshiba TA1372FNG chips and has 65mm x 37.5mm x 12mm can size.
21 pins on 2mm centers.
Half-NIM - 11 evenly spaced pins with no gap but much wider spacing (4mm?)
Pinout is not given. Looks like 2.5mm or 2.54mm header pins. 12 total pins with two gaps: 3 pins, skip 2, 7 pins, skip 2, 2 pins. Chip has two outputs, I and Q, both differential (4 wires total) instead of a simple IF output. Loop through antenna connections with no modulator.
DVB-T tuner with built in PAL/SECAM demodulator 22 pin dual row 2mm header. 48.5mm x 28.1mm x 7.6mm can size.
Actual tuner part number is hard to read
Microtune and Xceive make silicon tuner chips that don't need a can. Xceive has several models that claim to support all analog and digital TV standards from 42-864Mhz. Output is differential IF or demodulated analog video + demodulated mono audio or SIF multiplexed on the same pair of pins. XC5000 works with NTSC, PAL, SECAME, ATSC, OpenCable, DVB-T, DVB-C, ISDB-T, DMB-TH. Product briefs only. For tracking generators and software defined radio, the Microtune MT5100 upconverter takes a 36.125Mhz or 44Mhz IF and converts it to any frequency from 50Mhz to 860Mhz.
Linear Technology makes some direct conversion receiver chips with I/Q outputs. These would be easier to obtain in small quantities than tuners. These require an external 2x frequency synthesizer (simple diferential digital clock). The LT5546 is a 40Mhz to 500MHz variable gain amplifier and I/Q demodulator with 17Mhz baseband bandwidth. The LT 5517 demodulats from 40 to 900 Mhz and the LT5575 demodulates from 800 to 2700Mhz.
Cable modems send and receive which could facilitate software defined radio applications or tracking generators (though they tend to send and receive over the same connector which isn't good for network testing).
Microphonics have been observed with some CECB boxes. This is probably due to the capacitors on the input stage or possibly capacitors on the IF out. Avoid using certain types of ceramic capacitors that are prone to microphonics, particularly high density ones that are primarily designed for decoupling.
This file is maintained by Mark Whitis (whitis@freelabs.com).
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