HD Radio CODEC ID Test Report

Transcription

1 Report to the National Radio Systems Committee IBOC Standards Development Working Group HD Radio CODEC ID Test Report February 6, 2006 ibiquity Digital Corporation 8865 Stanford Boulevard, Suite 202 Columbia, Maryland (410)

2 This report provides an overview of the results of informal testing ibiquity conducted concerning a Codec identifier. After the adoption of NRSC-5, ibiquity was asked to examine the feasibility of implementing a Codec identifier that would allow receivers to determine the appropriate decompression software to use to decode a digital signal. The NRSC proposed Codec ID 15 be used to signal the use of a codec other than the HD Codec ( HDC ) used in the HD Radio system. This document describes the methodology and results of the laboratory tests that ibiquity employed in to complete this evaluation. A. Purpose of Evaluation The Codec ID Test was designed to evaluate the feasibility of implementing a Codec identifier for the HD Radio system. These tests were structured solely to evaluate the impact of the use of the proposed Codec ID on existing, commercially available HD Radio receivers. Specifically, the test evaluated the response when transmitting Codec ID 15 in the audio transport header (Table 5-2 SY_IDD_1017s). Existing HD Radio products are equipped with HDC. Therefore all codec ids other than ID=15 decode the digital audio using HDC. According to NRSC-5, the existing receivers should respond to ID=15 in the following manner: 1. Play only the analog audio 2. Have no apparent failure when detecting this configuration B. Transmission Configuration To determine the response of transmitting the Codec ID=15 (0b1111), several different receiver products were tested with the configuration shown in Figure 1. The HD Radio Test Exciter was configured to transmit an FM IBOC modulated waveform in accordance with NRSC-5. The test signal was formatted for MP3 transmission mode with the service characteristics listed in Table 1. The exciter was tuned to broadcast at MHz.

3 - 3 - Table 1 MP3 Service Characteristics Audio Service Analog Audio Content 1-kHz Audio CODEC Rate ID N/A N/A N/A PS Data Content MPS 2-kHz 64kbps 15 SPS1 N/A N/A N/A N/A SPS2 N/A N/A N/A N/A SPS3 400 Hz 24kbps 13 TALB: HD Radio Evaluation DDD TPE1: -4- test team -4- TIT2: fourth program test pattern #4# SPS4 N/A N/A N/A N/A SPS5 4-kHz 32kbps 15 SPS6 N/A N/A N/A N/A SPS7 N/A N/A N/A N/A

4 - 4 -!!"#$ Figure 1 CODEC ID Test Configuration C. Receiver Configuration ibiquity evaluated 12 different HD Radio receiver products in the test. The products listed in Table 2 included several multicast-enabled and non-multicast-enabled receivers. Each receiver was tuned to the test transmission frequency, MHz. The radios were evaluated for audio output, data display, and multicast selection.

5 - 5 - Table 2 HD Radio Receiver Products for CODEC ID Test Radio Product Product Category Multicast Enabled Kenwood HR-100MC Aftermarket car Yes Panasonic CBCQ9900 Aftermarket car No JVC KD-SHX900 Aftermarket car No BMW product OEM car Yes (modified) Yamaha RX-4600V Home AV Yes Boston Acoustics Tabletop Yes Recepter HD Audemat Aztec Golden Studio monitor Yes Eagle Alpine DVA-9965 Aftermarket car No JVC KD-HDR1 Aftermarket car Yes Rotel RT-1084 Home AV Yes Polk I-Sonic Tabletop Yes ibiquity Digital DRi- 352 Evaluation platform Yes D. Test Results The test results for the Codec ID evaluation are provided in Table 3. As seen in the table, receivers vary in their response to the Codec ID = 15. However, these results demonstrate that the proposed Codec ID cannot be introduced without a detrimental impact on the commercial receivers in use today. For example, several tests caused Radio B and Radio C to mute the analog audio and indicate incorrect Program Service Data display. The results also show that the radios responded improperly to Codec ID=13 for SPS-3, resulting in the loss of that program content. In summary, implementing Codec ID=15 will result in unstable behavior in current receiver products.

6 - 6 - Table 3 CODEC ID Test Results Radio Product Analog SIS MPS MPS PSD SPS-3 SPS-3 PSD SPS-5 Radio A 1kHz Tone None no blend None Radio B mute WTST no blend SPS_3 PSD Mute Yes Not Detected Radio C mute None no blend "Program not available" Mute Yes Not Detected Radio D 1kHz Tone WTST no blend None 1kHz Tone Yes Not Detected Radio E 1kHz Tone - no blend None Not Detected Not Detected Not Detected Radio F 1kHz Tone 0 0 None Radio G 1kHz Tone WTST no blend 0 Mute Yes Mute Radio H 1kHz Tone WTST no blend Radio I 1kHz Tone WTST no blend Blank Not Detected Not Detected Not Detected Radio J 1kHz Tone - no blend None Not Detected Not Detected Not Detected Radio K 1kHz Tone None no blend Not Detected Not Detected Not Detected Not Detected Radio L 1kHz Tone None no blend None Not Detected Not Detected Not Detected