ATA5423_06 ATMEL [ATMEL Corporation], ATA5423_06 Datasheet - Page 16

• Manufacturer Part Number: ATA5423_06
• Description: UHF ASK/FSK Transceiver
• Manufacturer: ATMEL [ATMEL Corporation]

16
ATA5423/25/28/29
Table 3-6.
The ATA5423/ATA5425/ATA5428/ATA5429 can also receive FSK and ASK modulated signals if
they are much higher than the I1dBCP. It can typically receive useful signals at 10 dBm. This is
often referred to as the nonlinear dynamic range which is the maximum to minimum receiving
signal and is 116 dB for 20 Kbit/s Manchester. This value is useful if two transceivers have to
communicate and are very close to each other.
Figure 3-5.
This high blocking performance even makes it possible for some applications using quarter
wave whip antennas to use a simple LC band-pass filter instead of a SAW filter in the receiver.
W h e n d e s i g n i n g s u c h a n L C f i l t e r t a k e i n t o a c c o u n t t h a t t h e 3 d B b l o c k i n g a t
433.92 MHz/2 = 216.96 MHz is 43 dBC and at 433.92 MHz/3 = 144.64 MHz is 48 dBC and at
2 × (433.92 MHz + 226 kHz) + –226 kHz = 868.066 MHz/868.518 MHz is 56 dBC. And espe-
cially that at 3 × (433.92 MHz + 226 kHz) + 226 kHz = 1302.664 MHz the receiver has its
second LO harmonic receiving frequency with only 12 dBC blocking.
Frequency Offset
+0.75 MHz
–
+1.5 MHz
–
+10 MHz
–
0.75 MHz
1.5 MHz
10 MHz
Blocking 6 dB Above Sensitivity Level with BER < 10
Close In 6 dB Blocking Characteristic and Image Response at 433.92 MHz
-10.0
60.0
40.0
30.0
20.0
70.0
50.0
10.0
0.0
-1.0
Distance of Interfering to Receiving Signal [MHz]
-0.8
-0.6
-0.4
Blocker Level
–
–
–
–
–
–
45 dBm
45 dBm
38 dBm
38 dBm
30 dBm
30 dBm
-0.2
0.0
0.2
0.4
0.6
–3
0.8
55 dBC/61 dBS
55 dBC/61 dBS
62 dBC/68 dBS
62 dBC/68 dBS
70 dBC/76 dBS
70 dBC/76 dBS
1.0
Blocking
4841C–WIRE–05/06