Funai argued against mandatory Analog Pass Thru feature, saying it would degrade sensitivity (only if you designed it wrong!!!), and indicated that affected users could readily install their own RF Splitters or A/B Switches (see item 49): http://www.ntia.doc.gov/ntiahome/frnotices/2007/DTVFinalRule_2e.htm I don't know what happened wrt argument to RETAIN NTSC in the existing demodulator chips, although they argued to make MTS/BTSC Stereo output optional.... Surely it COST MORE to modify chips to DELETE these functions. BTW: In AvsForum Antenna thread, I've looked at many different post-Feb2009 situations....MOST of them will have some NTSC stations. APT would also be useful for second TV's attached to Whole Home distribution systems, such as UHF TV2 output on DISH HD-DVR. ====================================== If you use an RF Splitter to feed a Converter Box and your old TV there is a 3.5-4.0+ dB loss of sensitivity. If you use a A/B Switch, it's under about 0.5 dB. [BTW: Radio Shack 15-1968 is a R/C A/B Switch.] The Thomson DTT76850 tuner is used in some Converter Boxes. A few (too few) came with the OPTIONAL Analog Pass Thru (APT) feature enabled....which is an RF Splitter and low-gain Preamp: https://gullfoss2.fcc.gov/prod/oet/forms/blobs/retrieve.cgi?attachment_id=923119&native_or_pdf=pdf The low-gain Preamp reduces the effect of the conventional tuner Noise Figure (typ. 8-10 dB) so overall Noise Figure is 8 dB (max). Given a thermal noise floor of -105.9 dBm (at 100-deg F) and 15.2 dB required SNR, theoretical ATSC sensitivity would be -90.7 dBm. With 8 dB NF, this is reduced to -82.7 dBm, barely meeting CECB sensitivity requirement of -83 dBm. [Not much wiggle room!!!!] Another approach would be to use PIN Diode switches to select either CH3/4 CECB output or Antenna input. However, in order to meet FCC Output to Input isolation requirements, a low-gain Preamp would still be needed. Both approach puts a drain on the Energy Star power budget. Making it hard for APT to work in a CECB with power "OFF". Most are selected via menu entry when "ON". holl_ands ====================================== "Hunold, Ken" <KRH@xxxxxxxxx> wrote: Perhaps you might need an analog tuner after next February, but I'd venture a guess that the vast majority of other users would have no need for another NTSC tuner and would benefit from the few extra dB of sensitivity. A few of the CECBs have the smart antenna interface. There used to be some comparison spreadsheets posted, but I can't find them now. The RCA unit has the interface, and there are others. Unfortunately, there aren't many smart antennas available. More chicken-and-egg, I guess. Ken -----Original Message----- From: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] On Behalf Of Craig Birkmaier Sent: Wednesday, May 21, 2008 9:28 AM To: opendtv@xxxxxxxxxxxxx Subject: [opendtv] Re: CBA and Microprose team up on NTIA DTV Boxes At 9:10 AM -0400 5/21/08, Hunold, Ken wrote: >I'd rather see a smart antenna interface (which I can't add myself) and >more smart antennas. I'm using such a setup now, and while I don't >need all the capabilities of the smart antenna in my >high-signal-strength location, I did see a difference at home. I'd rather see an integrated analog tuner, like those in EVERY new HDTV capable receiver sold in the U.S. today. It was sheer stupidity to remove (or disable) these tuners from the NTIA DTV box specifications. By the way, the NTIA specs do allow for a smart antenna interface, however I have not seen this feature in any NTIA approved box. Regards Craig ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line. ----------------------------------------- This message (including any attachments) may contain confidential information intended for a specific individual and purpose. If you are not the intended recipient, delete this message. If you are not the intended recipient, disclosing, copying, distributing, or taking any action based on this message is strictly prohibited. ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.