Videolarm qfdpt3-50na 用户指南

- 5 -

250 ft

3 4 5 8

300 ft

4 5 6

400 ft

5 6 8

500 ft

6 8

16 26

600 ft

10 12 19 31

800 ft

10 13 16 25 42

1000 ft

13 16 20 32 52

1250 ft

16 20 25 40 65

1500 ft

19 24 30 48 78

1750 ft

23 28 35 55 91

2000 ft

26 32 40 63

104

2500 ft

32 40 49 79

131

3000 ft

39 48 59 95

157

3500 ft

45 56 69

111

183

4000 ft

52 64 79

127

209

5000 ft

65 80 99

158

261

6000 ft

78 95 119 190 313

8000 ft

104 127 158 253 418

Unshielded Twisted-Pair Wire Gauge (AWG)

Cable

Distance

Unshielded Twisted-Pair Wire Gauge (AWG)

Distance

Unshielded Twisted-Pair Wire Gauge (mm)

Distance

0.5

0.6

0.7

0.8

1.0

3 4 5 8

4 5 6

5 7 8

6 8

16 26

10 13 21 34

13 16 19 31 51

17 21 26 42 69

21 26 32 52 86

26 31 39 62

103

32 39 49 78

129

38 47 58 94

154

43 52 65

104

171

51 63 78

125

206

64 78 97

156

257

77 94 117 187 309

102 125 156 249 411

Cable

75 m

100 m

125 m

150 m

200 m

300 m

400 m

500 m

600 m

750 m

900 m

1000 m

1200 m

1500 m

1800 m

2400 m

75 m

100 m

125 m

150 m

200 m

300 m

400 m

500 m

600 m

750 m

900 m

1000 m

1200 m

1500 m

1800 m

2400 m

3 5 6 9

4 7 9

6 8

15 22

10 13 18 27

13 17 24 36

13 20 26 36 54

18 27 35 48 72

22 33 43 60 90

26 40 52 72

108

33 50 65 89

135

40 60 78

107

162

44 66 86

119

179

53 80

104

143

215

66 100 130 179 269

79 120 155 215 323

106 159 207 286 431

Wiring Notes

Wire — What to DO

1. DO use point-to-point Unshielded Twisted Pair wire, gauge 24 or

thicker, stranded or solid, Category 2, 3, 4, or 5.

2. The video signal may co-exist in the same wire bundle as other

video, telephone, data, control signals, or low-voltage power. It
is also OK to run NVT video signals in or near electromagnetic
fields (in accordance with National Electrical Code, local, or other
local safety requirements).

3. DO measure the wire distance. Use only transceivers that are

designed for that distance.

4. DO make sure the pair of wires carrying the video signal is sent

as a twisted pair

(e.g. the blue-white/white-blue wires twisted

together as a pair), not a “split-pair” (e.g. blue-white conductor,
part of one pair/orange-white conductor, part of another pair).

Wire — What NOT to DO

1. DO NOT USE SHIELDED TWISTED PAIR WIRE. It will severely

degrade the distance performance. Short runs may be used with
some signal degradation (for example elevator traveler cables).
Multi-pair wire with an overall shield is OK.

2. DO NOT USE UN-TWISTED WIRE. It will reduce the NVT

product’s inherent interference immunity.

3. DO NOT allow your installation to have “bridge-taps”, loading

coils, talk-battery, or MOV type protectors. Bridge-taps are where
a twisted pair is connected to two twisted pairs (such as an
extension phone at home). Bridge-taps cause reflections as the
signal propagates, resulting in “ghosts” in the video image, and
are to be avoided.

4. If the phone company is providing the cable runs between

buildings, make sure it’s “dry copper” i.e. it should have none
of the following: dial-tone, 48 volts, loading coils, bridge-taps,
switching, or long paths to the phone company’s central office
and back.

5. Due to near-end crosstalk, DO NOT send a transmit and a

receive signal in the same wire bundle. Exceptions: Less than
1,000 ft (300m), or Category 5 cable, up to 2,000 ft (600m) are
OK.

6. DO NOT send “Up-the-Coax” Pan/Tilt/Zoom signals through

active (amplified) NVT transceivers.

Measure your wire distance

Note: All NVT quoted distance specifications include any coax in the
run. It is recommended that the wire distance be measured to ensure
that the capability of the NVT product is correct.

Wire resistance may be measured with an ohm-meter by shorting
the two conductors together at the far end, and measuring the loop-
resistance out and back. Compare your readings with the charts in
the next column.

7. For safety, never put NVT signals in the same conduit as

high-voltage wiring.

8. WARNING — to reduce a risk of fire or electrical shock, do

not expose this product to rain or moisture.