[Code of Federal Regulations]
[Title 47, Volume 5]
[Revised as of October 1, 2006]
From the U.S. Government Printing Office via GPO Access
[CITE: 47CFR87.151]
[Page 201-202]
TITLE 47--TELECOMMUNICATION
CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION (CONTINUED)
PART 87_AVIATION SERVICES--Table of Contents
Subpart D_Technical Requirements
Sec. 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
[[Page 202]]
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.
------------------------------------------------------------------------
Maximum level of undesired
Frequency \1\ 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
------------------------------------------------------------------------
\1\ The 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.
------------------------------------------------------------------------
Maximum
level of
undesired
Frequency \1\ signal at
the
receiver
input (dBm)
------------------------------------------------------------------------
88 MHz <= f <= 102 MHz..................................... 15
104 MHz.................................................... 10
106 MHz.................................................... 5
107.9 MHz.................................................. -10
------------------------------------------------------------------------
\1\ The 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.
------------------------------------------------------------------------
Maximum
level of
undesired
Frequency \1\ signal at
the
receiver
input (dBm)
------------------------------------------------------------------------
88 MHz <= f <= 104 MHz..................................... 15
106 MHz.................................................... 10
107 MHz.................................................... 5
107.9 MHz.................................................. 0
------------------------------------------------------------------------
\1\ The 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]