Originally Posted by RegGuheert
I think multi-conversion tuners are coming at a lower cost than the current batch of single-conversion tuners. Microtune sells such a tuner for less than $3 today. Please have a look at their MT2131.
I tried to post a URL to the product datasheet, but the forum would not let me post it since I'm new here.
P.S. Thanks for all the info on the Samsung DTB-H260F!! I think I will hold off, as my Hughes HIRD-E86 now receives both NTSC and ATSC. It's not perfect, but having NTSC support makes up for some of it's failures. Hopefully better ATSC receivers are yet to come!
Microtune's Double Conversion Tuner chip discussion began in this post:http://www.avsforum.com/avs-vb/showt...ne#post7209568
Read down for couple days of discussion....
Microtune website is here:http://hraunfoss.fcc.gov/edocs_publi...C-05-199A1.pdf
MT2131 Spec sheet and their "benchmark comparison report" is here:http://www.microtune.com/products/pd...1_tuner_ic.pdfhttp://www.microtune.com/products/pd...benchmarks.pdf
I provided a link to two technical articles written by John Norsworth of Microtune here:http://www.freelists.org/archives/op.../msg00028.html
He presents the double conversion tuner being used WITHOUT an RF Tuned Bandbass Filter on the input--
which of course results in better Sensitivity (e.g. Noise Figure) by eliminating the loss in an RF inductor and Varactor Diode
(voltage variable capacitor for tuning input RF filter).....and makes for a much more compact design that could fit into a USB Stick.
However, the RF Tuned Bandpass Filter (typical bandwidth of 10-20 MHz) on the input of a single conversion tuner
plays a very important role in suppressing strong stations so that you can receive a desired weak signal.
Hence, the primary use for a double conversion tuner would be on a cable system where all the signals are roughly
the same strength, so the tuner doesn't have to try to receive a weak signal among many other strong signals.
Microtune cites improved performance for adjacent channel performance (D/U ratios), which would be
nearly unaffected with or without an input RF Bandpass Filter.
What has NOT yet been revealed is how much sensitivity is lost from overload from ALL the other channels
across the entire band if an input RF Bandpass Filter is not used....hopefully, an OTA tuner would not forgo the input RF Bandpass filter...
FYI: The FCC sponsored a series of tests on various OTA STBs and HDTVs (sshhh!!! no names!!!!):http://hraunfoss.fcc.gov/edocs_publi...C-05-199A1.pdf
See page 31 for Sensitivity and page 34 for ability to decode the A/74 Field Ensembles.