Preliminary
11-44
RF2516
Rev A10 010613
11
This equation is derived from the endpoints of the fre-
quency range and their respective field strengths. Note
that the field strength is in microvolts per meter and the
frequency is in megahertz. To determine the spurious
level, divide the level calculated above for the spurious
frequency by ten.
As an example, assume the fundamental is 315MHz
and the reference frequency is 9.8MHz. The field
strengths of the fundamental, the reference spurs, and
the harmonics of the fundamental up through the tenth
harmonic are calculated in the following table The
occupied bandwidth limit is 787.5 kHz. As shown in
Table A, the fifth, seventh, and ninth harmonics fall into
restricted bands as called out in section 15.205. The
limits for these restricted bands are called out in sec-
tion 15.209. The power level in the last column is the
level if the output is connected directly to a spectrum
analyzer. Refer to Appendix A as to how this column
was calculated.
Local Oscillator Source
Since the RF2516 has a phase-locked VCO, it can be
used as a signal source. The device is an ASK/OOK
transmitter, with the data provided at the MOD IN pin.
When theMOD IN is ahighlogiclevel, the carrier is
transmitted. When MOD IN is a low logic level, then the
carrier is not transmitted. Therefore, to use the RF2516
as signal source, simply tie the MOD IN pin to the sup-
ply voltage, through a suitable series resistor (mini-
mum 3k
Ω).
Conclusions
The RF2516 is an AM/OOK VHF/UHF transmitter that
features a phase-locked output. This device is suitable
for use in a CFR Part 15.231 compliant product as well
as a local oscillator signal source. Two examples show-
ing these applications were discussed.
The RF2516 is packaged in a low-cost plastic package
and requires few external parts, thus making it suitable
for low-cost designs.
Table A
Frequency
(MHz)
15.205 Limits
(
µV/m@3m)
15.231 Limits
(
µV/m@3m)
Final FCC Mask
(
µV/m@3m)
Final FCC Mask
(
µV/m@3m)
Power Level
(dBm, 50
Ω)
Ref Spur
305.2
-
604.17
604.17
55.62
-39.61
1
315.0
-
6041.67
6041.67
75.62
-19.61
Ref Spur
324.8
-
604.17
604.17
55.62
-39.61
2
630.0
-
604.17
604.17
55.62
-39.61
3
945.0
-
604.17
604.17
55.62
-39.61
4
1260.0
-
604.17
604.17
55.62
-39.61
5
1575.0
500
-
500.00
53.98
-41.25
6
1890.0
-
604.17
604.17
55.62
-39.61
7
2205.0
500
-
500.00
53.98
-41.25
8
2520.0
-
604.17
604.17
55.62
-39.61
9
2835.0
500
-
500.00
53.98
-41.25
10
3150.0
-
604.17
604.17
55.62
-39.61
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