Goto Section: 87.149 | 87.169 | Table of Contents
FCC 87.151
Revised as of October 2, 2015
Goto Year:2014 |
2016
§ 87.151 Special requirements for differential GPS receivers.
(a) The receiver shall achieve a message failure rate less than or equal to
one failed message per 1000 full-length (222 bytes) application data
messages, while operating over a range from −87 dBm to −1 dBm, provided that
the variation in the average received signal power between successive bursts
in a given time slot shall not exceed 40 dB. Failed messages include those
lost by the VHF data receiver system or which do not pass the cyclic
redundancy check (CRC) after application of the forward error correction
(FEC).
(b) The aircraft receiving antenna can be horizontally or vertically
polarized. Due to the difference in the signal strength of horizontally and
vertically polarized components of the broadcast signal, the total aircraft
implementation loss is limited to 15 dB for horizontally polarized receiving
antennas and 11 dB for vertically polarized receiving antennas.
(c) Desensitization. The receiver shall meet the requirements specified in
paragraph (a) of this section in the presence of VHF-FM broadcast signals in
accord with following tables.
(1) Maximum levels of undesired signals.
Frequency^1 Maximum level of undesired signal at the receiver input (dBm)
50 kHz up to 88 MHz −13
88 MHz-107.900 MHz [see paragraph (c)(2)]
108.000 MHz-117.975 MHz excluded
118MHz −44
118.025 MHz −41
118.050 MHz up to 1660.5 MHz −13
^1The relationship is linear between single adjacent points designated by
the above frequencies.
(2) Desensitization frequency and power requirements for the frequencies
108.025 MHz to 111.975 MHz.
Frequency^1 Maximum level of undesired signal at the receiver input (dBm)
88 MHz ≤f ≤102 MHz 15
104 MHz 10
106 MHz 5
107.9 MHz −10
^1The relationship is linear between single adjacent points designated by
the above frequencies.
(3) Desensitization frequency and power requirements for the frequencies
112.00 MHz to 117.975 MHz.
Frequency^1 Maximum level of undesired signal at the receiver input (dBm)
88 MHz ≤f ≤104 MHz 15
106 MHz 10
107 MHz 5
107.9 MHz 0
^1The relationship is linear between single adjacent points designated by
the above frequencies.
(d) Intermodulation immunity. The receiver shall meet the requirements
specified in paragraph (a) of this section in the presence of interference
from two-signal, third order intermodulation products of two VHF-FM
broadcast signals having levels in accordance with the following:
(1) 2N1 + N2 + 72 ≤0 for VHF-FM sound broadcasting signals in the range
107.7-108 MHz; and
(2) 2N1 + N2 + 3 (24 −20log delta f/0.4) ≤0 for VHF-FM sound broadcasting
signals below 107.7 MHz, where the frequencies of the two VHF-FM sound
broadcasting signals produce, within the receiver, a two signal, third-order
intermodulation product on the desired VDB frequency.
(3) In the formulas in paragraphs (d)(1) and (d)(2) of this section, N1 and
N2 are the levels (dBm) of the two VHF FM sound broadcasting signals at the
VHF data broadcast (VDB) receiver input. Neither level shall exceed the
desensitization criteria set forth in paragraph (c) of this section. Delta f
= 108.1 − f1, where f1 is the frequency of N1, the VHF FM sound broadcasting
signal closer to 108.1 MHz.
[ 69 FR 32881 , June 14, 2004]
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Subpart E—Frequencies
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Goto Section: 87.149 | 87.169
Goto Year: 2014 |
2016
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