HiDef Radio 1.1-beta1 (build 20)

A beta of 1.1: analog AM. Until now AM was HD only. Now every AM station plays, with the same blend to HD as on FM.

New: analog AM

• Analog AM with a synchronous detector, the kind HD-ready AM radios use. Tune any AM station and the sound starts in analog.
• Blend to HD on AM, like on FM: in Auto the analog plays first, and once the app has lined the two up it crossfades to HD (about 15-20 s after tuning on AM). In Auto, AM sound starts about 3 seconds after you tune, because the analog plays that far behind live so the blend can see HD dropouts coming.
• C-QUAM AM stereo for the stations that still send it ("ST" on the signal line). It is switched off while an HD signal is in sync, because a hybrid HD station's digital carriers sit where C-QUAM puts its stereo.
• AM signal meter: "Analog AM ▮▮▮▮▯" shows the carrier-to-noise ratio. The signal details show it in dB, plus the carrier level, the offset and the stereo state.
• Settings: "FM stereo" is now "Stereo" (it covers C-QUAM too), and there is a new AM audio bandwidth setting (3 / 5 / 8 / 10 kHz, 5 by default).
• A favorite saved from an AM station without HD shows as "1260 AM". The welcome card mentions AM again.

Also

• RTL-SDR Blog V4 Lite (V4L): the driver already supported it. The debug info now names its tuner correctly (R828S) instead of calling it an R820T. Nobody has tried a V4L with the app yet - reports welcome.

Good to know - please test

• Heard on the air so far: KHTS 1220 (no HD). The AM blend has been proven on recordings of KMZT 1260 and KBRT 740, but not yet on the air.
• C-QUAM has only been tested on a made-up signal. If you have a C-QUAM station nearby, please say whether left and right come out the right way round. If you can provide me a recorded IQ (cu8) sample file, even better.
• The AM meter's bars are a first guess. Tell me how they compare with what you hear.
• A V3 (direct sampling) on AM should work but is not confirmed yet.
• Most helpful in a report: station and frequency, your dongle, what the signal line said, and the AM line from the speed test ("Show debug info" → "Run speed test").

Installing

This is a pre-release on GitHub only. The Google Play test stays on 1.0 for now. It is signed with the same key as the earlier GitHub releases, so it installs over 1.0 from GitHub and your favorites stay. If you installed from Google Play, you have to uninstall that copy first (Android won't mix the two signatures), and your favorites won't carry over.

HiDefRadio-1.1-beta1-build20.apk SHA-256:
cca53488311129d1ab4fa8fd5c9064e1328c35ddbd504639ff71f6a56153376d