9. SET commands
9.1. SET_MOD_CHANNEL [0x0E]
In the case that more than one 3D TOF cameras (or in general high frequency modulated illumination sources, higher than several MHz)
operate in the same scenery, 3D TOF cameras can get disturbed by interference effects. ESPROS 3D TOF cameras operate on the
synchronous demodulation principle (super-heterodyne demodulation) which is like a narrow frequency bandpass filter given by the
modulation frequency. Modulated light by a “disturber” needs to operate at the same or very similar frequency to disturb an ESPROS
3D TOF camera. However, if the “disturber” operates in this narrow frequency band, it may interfere other cameras.
Interference detection
The TOF>cam 635 has a built in interference detection which detects pixels with wrong distance data due to interference. The distance
data of such interfered pixels are either marked with 'not valid' or return the last measurement value.
Interference avoidance
To prevent interference, the TOF>cam 635 camera has an option to slightly change the modulation frequency in order to “shift” away from
a disturbers frequency. Therefore, the camera has predefined “modulation channels”, each preset with a slightly shifted modulation
frequency.
The camera can be set either to a fixed channel or an automatic frequency hopping mode. In the automatic frequency hopping mode, the
camera “hops” to a different frequency if it detects interference.
Parameter
byte 0:
reserved
bit 2...7: 0
byte 1:
Channel 0 … 15,
default
: Channel 0
others:
0x00
Response type
0x00:
ACK
Response time
t
PROC
:
~ 25µs
Example
Command e.g.
| 0xF5 |
0x0E
|
0x01
0x01
0x00 0x00 0x00 0x00 0x00 0x00
| 0xBD 0xAA 0x58 0xFC | (Frequency hopping ON,
channel 1)
Channel
NFOV frequency
center frequency 10MHz
WFOV frequency
center frequency 20MHz
0
10.00
20.00
1
9.60
19.20
2
9.65
19.30
3
9.70
19.40
4
9.75
19.50
5
9.80
19.60
6
9.85
19.70
7
9.90
19.80
8
9.95
19.90
9
10.05
20.10
10
10.10
20.20
11
10.15
20.30
12
10.20
20.40
13
10.25
20.50
14
10.30
20.60
15
10.35
20.70
Table 9: Modulation channels
© 2019 ESPROS Photonics Corporation
Characteristics subject to change without notice
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Installation_and_Operation_Manual_TOF>cam_635-V0.21