Technical information
Instruments
Digital or Analogue In House AV
Distribution Systems
It is practical to send the picture and sound from a PayTV receiver,
DVD player or recorder to all TVs in the house. There are several
ways to accomplish this, but careful thought must be given to
channel planning and system design if it is to allow any channel to
be viewed clearly on any TV at any time.
Most RF outputs are factory preset around channel 37 and are
menu adjustable across the entire ch 28 to 69 UHF TV range. To
permit a DVR to record off-air channels, a small amount of incoming
signal should be tapped off before the mixer to avoid creating a
feedback loop. Laceys.tv FA1-12 or CD-141 couplers will provide the
DVR with off air signal with a hardly noticeable insertion loss of less
than 1dB. An external modulator like Laceys.tv MD531 with Stereo
Audio and a broad channel plan may assist.
Laceys.tv pioneered the use of Digital Modulators in 2008. Today
we are delivering quality HD and SD Digital TV modulators, solutions
that get the best from your clients Digital TVs whether it is a single
door camera or many channels from various AV sources. The result is
superior digital pictures over ordinary analogue picture quality.
Mixing with a splitter or power divider in reverse effectively
superimposes any unwanted off air signals and noise etc. from the
DVD or PayTV box modulator, on to the signals you want in your
system. Laceys.tv have a range of band or frequency selective
mixing devices that offer high isolation, generally better than 30dB,
and insertion loss of less than 1dB, that can make the ideal mix. For
example, M1-4/5FV will mix signal from an off-air antenna up to
ch36 with ch40 upwards. If a number of set top boxes are required,
their RF outputs can be combined using an F type splitter in reverse
and the combined signal fed into a band selective mixer. Another
solution is the JH7RP45AU distribution amplifier which provides
selective inputs for all VHF, bands 4 and band 5. Grossly unbalanced
signal levels can be adjusted with attenuators.
Ideally, multiple set top boxes and off-air channels should be
combined with a single channel amplifier system like Lacey’s KF
series filters, although cost sometimes dictates a band selective
solution like those described above. With the typical 65-70dBμV
from a modulator and 70dBμV of off-air signal, it is possible to run a
modulated system to 4 points passively using an FA1-12 or CD-141
coupler and M1-4/5FV mixer, with the total loss in the 2 devices
<2dB. No amplifier is necessary!
LEVEL CONVERSION TABLE AT 75 OHMS
dBμV μV dBm pW
25 17.8 -83.8 4.22
27 22.4 -81.8 6.68
29 28.2 -79.8 10.6
31 35.5 -77.8 16.8
33 44.7 -75.8 26.6
35 56.2 -73.8 42.2
37 70.8 -71.8 66.8
39 89.1 -69.8 106
41 112 -67.8 168
43 141 -65.8 266
45 178 -63.8 422
47 224 -61.8 668
49 282 -59.8 1.06nW
51 355 -57.8 1.68
53 447 -55.8 2.66
55 562 -53.8 4.22
57 708 -51.8 6.68
59 891 -49.8 10.6
61 1.12mV -47.8 16.8
63 1.41 -45.8 26.6
65 1.78 -43.8 42.2
67 2.24 -41.8 66.8
69 2.82 -39.8 106
71 3.55 -37.8 168
73 4.47 -35.8 266
75 5.62 -33.8 422
77 7.08 -31.8 668
79 8.91 -29.8 1.06μW
81 11.2 -27.8 1.68
83 14.1 -25.8 2.66
85 17.8 -23.8 4.22
dBμV mV dBm μW
87 22.4 -21.8 6.68
89 28.2 -19.8 10.6
91 35.5 -17.8 16.8
93 44.7 -15.8 26.6
95 56.2 -13.8 42.2
97 70.8 -11.8 66.8
99 89.1 -9.8 106
101 112 -7.8 168
103 141 -5.8 266
105 178 -3.8 422
107 224 -1.8 668
109 282 .2 1.06mW
111 355 2.2 1.68
113 447 4.2 2.66
115 562 6.2 4.22
117 708 8.2 6.68
119 891 10.2 10.6
121 1.12V 12.2 16.8
123 1.41 14.2 26.6
125 1.78 16.2 42.2
127 2.24 18.2 66.8
129 2.82 20.2 106
131 3.55 22.2 168
133 4.47 24.2 266
135 5.62 26.2 422
137 7.08 28.2 668
139 8.91 30.2 1.06W
141 11.2 32.2 1.68
143 14.1 34.2 2.66
145 17.8 36.2 4.22
147 22.4 38.2 6.68
ANTENNA
PVR
COUPLER
FA1-12
RF IN
MIXER
M1-4/5FV
AMPLIFIER
AI100
MULTI
TAP
FA8-MT
RF OUT
OUT TO
TV’S
Catalogue 106
104