Analog Headend System
Traditionally We were using the Analog Headend system. So in 860Mhz the maximum number of channels which analog headend system supports are 106.
As we all know number of channels are growing day by day. So it was not possible to provide more than 106 tv channels in analog headend system. Then we need to go for Digital Headend System.
But in this article we will describe the Analog Headend System only.
In analog headend system we need to have RF from dishes and then put them into the decoders. These decoders provides the Composite Video Signal. Now instead of encoders we insert this Composite Video Signal into Modulators directly.
These modulators are having different frequencies. Analog headend frequency chart is mentioned below,
PAL B/G FREQUENCY CHART | |||||||
SR.NO. | CHANNEL | CARRIERS | SL.NO. | CHANNEL | CARRIERS | ||
VIDEO MHz | AUDIO MHz | VIDEO MHz | AUDIO MHz | ||||
BAND I | U H F | ||||||
1 | E2 | 48.25 | 53.75 | 58 | UHF21 | 471.25 | 476.75 |
2 | E3 | 55.25 | 60.75 | 59 | UHF22 | 479.25 | 484.75 |
3 | E4 | 62.25 | 67.75 | 60 | UHF23 | 487.25 | 492.75 |
MID BAND | 61 | UHF24 | 495.25 | 500.75 | |||
4 | X | 69.25 | 74.75 | 62 | UHF25 | 503.25 | 508.75 |
5 | Y | 76.25 | 81.75 | 63 | UHF26 | 511.25 | 516.75 |
6 | Z | 83.25 | 88.75 | 64 | UHF27 | 519.25 | 524.75 |
7 | Z+1 | 90.25 | 95.75 | 65 | UHF28 | 527.25 | 532.75 |
8 | Z+2 | 97.25 | 102.75 | 66 | UHF29 | 535.25 | 540.75 |
9 | S1 | 105.25 | 110.75 | 67 | UHF30 | 543.25 | 548.75 |
10 | S2 | 112.25 | 117.75 | 68 | UHF31 | 551.25 | 556.75 |
11 | S3 | 119.25 | 124.75 | 69 | UHF32 | 559.25 | 564.75 |
12 | S4 | 126.25 | 131.75 | 70 | UHF33 | 567.25 | 572.75 |
13 | S5 | 133.25 | 138.75 | 71 | UHF34 | 575.25 | 580.75 |
14 | S6 | 140.25 | 145.75 | 72 | UHF35 | 583.25 | 588.75 |
15 | S7 | 147.25 | 152.75 | 73 | UHF36 | 591.25 | 596.75 |
16 | S8 | 154.25 | 159.75 | 74 | UHF37 | 599.25 | 604.75 |
17 | S9 | 161.25 | 166.75 | 75 | UHF38 | 607.25 | 612.75 |
18 | S10 | 168.25 | 173.75 | 76 | UHF39 | 615.25 | 620.75 |
BAND III | 77 | UHF40 | 623.25 | 628.75 | |||
19 | E5 | 175.25 | 180.75 | 78 | UHF41 | 631.25 | 636.75 |
20 | E6 | 182.25 | 187.75 | 79 | UHF42 | 639.25 | 644.75 |
21 | E7 | 189.25 | 194.75 | 80 | UHF43 | 647.25 | 652.75 |
22 | E8 | 196.25 | 201.75 | 81 | UHF44 | 655.25 | 660.75 |
23 | E9 | 203.25 | 208.75 | 82 | UHF45 | 663.25 | 668.75 |
24 | E10 | 210.25 | 215.75 | 83 | UHF46 | 671.25 | 676.75 |
25 | E11 | 217.25 | 222.75 | 84 | UHF47 | 679.25 | 684.75 |
26 | E12 | 224.25 | 229.75 | 85 | UHF48 | 687.25 | 692.75 |
S U P E R B A N D | 86 | UHF49 | 695.25 | 700.75 | |||
27 | S11 | 231.25 | 236.75 | 87 | UHF50 | 703.25 | 708.75 |
28 | S12 | 238.25 | 243.75 | 88 | UHF51 | 711.25 | 716.75 |
29 | S13 | 245.25 | 250.75 | 89 | UHF52 | 719.25 | 724.75 |
30 | S14 | 252.25 | 257.75 | 90 | UHF53 | 727.25 | 732.75 |
31 | S15 | 259.25 | 264.75 | 91 | UHF54 | 735.25 | 740.75 |
32 | S16 | 266.25 | 271.75 | 92 | UHF55 | 743.25 | 748.75 |
33 | S17 | 273.25 | 278.75 | 93 | UHF56 | 751.25 | 756.75 |
34 | S18 | 280.25 | 285.75 | 94 | UHF57 | 759.25 | 764.75 |
35 | S19 | 287.25 | 292.75 | 95 | UHF58 | 767.25 | 772.75 |
36 | S20 | 294.25 | 299.75 | 96 | UHF59 | 775.25 | 780.75 |
H Y P E R B A N D | 97 | UHF60 | 783.25 | 788.75 | |||
37 | S21 | 303.25 | 308.75 | 98 | UHF61 | 791.25 | 796.75 |
38 | S22 | 311.25 | 316.75 | 99 | UHF62 | 799.25 | 804.75 |
39 | S23 | 319.25 | 324.75 | 100 | UHF63 | 807.25 | 812.75 |
40 | S24 | 327.25 | 332.75 | 101 | UHF64 | 815.25 | 820.75 |
41 | S25 | 335.25 | 340.75 | 102 | UHF65 | 823.25 | 828.75 |
42 | S26 | 343.25 | 348.75 | 103 | UHF66 | 831.25 | 836.75 |
43 | S27 | 351.25 | 356.75 | 104 | UHF67 | 839.25 | 844.75 |
44 | S28 | 359.25 | 364.75 | 105 | UHF68 | 847.25 | 852.75 |
45 | S29 | 367.25 | 372.75 | 106 | UHF69 | 855.25 | 860.75 |
46 | S30 | 375.25 | 380.75 | ||||
47 | S31 | 383.25 | 388.75 | ||||
48 | S32 | 391.25 | 396.75 | ||||
49 | S33 | 399.25 | 404.75 | ||||
50 | S34 | 407.25 | 412.75 | ||||
51 | S35 | 415.25 | 420.75 | ||||
52 | S36 | 423.25 | 428.75 | ||||
53 | S37 | 431.25 | 436.75 | ||||
54 | S38 | 439.25 | 444.75 | ||||
55 | S39 | 447.25 | 452.75 | ||||
56 | S40 | 455.25 | 460.75 | ||||
57 | S41 | 463.25 | 468.75 |
As you can see above in table there are total 106 channels are available for analog headend system. So there are one particular modulator for one particular frequency.
These modulators are having Composite Video Signal as input and RF signal as output for particular frequency. All the outputs from these modulators are combined together via combiner and then single output goes into the splitter. This splitter split the output for different transmitters.
So transmitters are having RF input and gives Optical Fiber output.These optical fibers are deployed in different locations for Cable Operators.
At the LCO or Operator end we install a NODE. This node takes optical input and gives RF output. We gives Power Supply input also to the node as supply.Thus output of node goes into the amplifiers as input. Then amplifiers amplify the signal and gives amplified output. This output goes into the set up box as RF Input at subscriber end.
This was all about the analog headend system.