ATA5823 ATMEL Corporation, ATA5823 Datasheet - Page 16

• Manufacturer Part Number: ATA5823
• Description: Uhf Ask/fsk Transceiver Ata5823 Ata5824
• Manufacturer: ATMEL Corporation

16
ATA5823/ATA5824
Table 7-6
cies. Note that sometimes the blocking is measured relative to the sensitivity level
(denoted dBS) instead of the carrier
Table 7-6.
The ATA5823/ATA5824 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 which is
115.5 dB for 433.92 MHz/FSK/20 Kbit/s/±19.5 kHz/ Manchester. This value is useful if two
transceivers have to communicate and are very close to each other.
In a keyless entry system there is another blocking characteristic that has to be considered. A
keyless entry system has a typical service range of about 30 m with a receiver sensitivity of
about
important to know how large this blockers can be until the system doesn’t work anymore and the
user has to use its key. With a recommended sensitivity of about
just around the car.
important case with a useful signal of
Manchester.
As can be seen the system works even with blockers above the compression point. This is due
to a wide bandwidth automatic gain control that begins to work if blockers above the compres-
sion point are at the antenna input and increasing the current in the LNA/Mixer to get a better
compression point needed to handle these large blockers.
Figure 7-6.
–
Frequency Offset
106 dBm to
shows the blocking performance measured relative to
+0.75 MHz
–0.75 MHz
+1.0 MHz
–1.0 MHz
+1.5 MHz
–1.5 MHz
+10 MHz
–10 MHz
Blocking 3 dB Above Sensitivity Level with BER < 10
±2.5 MHz Blocking Characteristic for
Figure 7-6
–
109 dBm. In some cases, large blockers limit this service range, and it is
-20.0
-30.0
-40.0
-50.0
-60.0
-70.0
-80.0
-90.0
-2.5
Distance of Interfering to Receiving Signal [MHz]
and
-2.0
Figure 7-7 on page 17
-1.5
–
102.5 dBm (denoted dBC).
-1.0
Blocker Level
–47.5 dBm
–47.5 dBm
–44.5 dBm
–44.5 dBm
–42.0 dBm
–42.0 dBm
–35.5 dBm
–35.5 dBm
–
85dBm 433.92 MHz/FSK/20 Kbit/s/±19.5 kHz/
-0.5
0.0
–
85 dBm Useful Signal at 433.92 MHz
0.5
show the blocking performance in this
1.0
1.5
–
102.5 dBm for some frequen-
–
-3
85 dBm, the system works
2.0
55.0 dBC/58.0 dBS
55.0 dBC/58.0 dBS
58.0 dBC/61.0 dBS
58.0 dBC/61.0 dBS
60.5 dBC/63.5 dBS
60.5 dBC/63.5 dBS
67.0 dBC/70.0 dBS
67.0 dBC/70.0 dBS
2.5
Blocking
4829D–RKE–06/06
–
105.5 dBm