INVERTED CDCSS (DPL) CONVERSION CHART

[Voyager]

This subject came up on the BCD396T Yahoo Group. "When are the scanner manufacturers going to support inverted DPLs?" Well, the truth is they have since they started supporting DPLs at all.

EVERY inverted DPL code is the same as a standard (non-inverted) code.

Here is a 'chart' you can look up your own. BTW, the codes
are mutually exclusive. If you look up one on the left as a standard
code, the one on the right is the equivallent inverted code. If you have
an inverted code, look that up on the left and the one on the right will
be the standard code. These are the standard 104 codes. If you have one
not on the list, email me.

Now you can program all those 'inverted' code users in your scanner!

023 047
025 244
026 464
031 627
032 051
036 172
043 445
047 023
051 032
053 452
054 413
065 271
071 306
072 245
073 506
074 174
114 712
115 152
116 754
122 225
125 365
131 364
132 546
134 223
143 412
145 274
152 115
155 731
156 265
162 503
165 251
172 036
174 074
205 263
212 356
223 134
225 122
226 411
243 351
244 025
245 072
246 523
251 165
252 462
255 446
261 732
263 205
265 156
266 454
271 065
274 145
306 071
311 664
315 423
325 526
331 465
332 455
343 532
346 612
351 243
356 212
364 131
365 125
371 734
411 226
412 143
413 054
423 315
431 723
432 516
445 043
446 255
452 053
454 266
455 332
462 252
464 026
465 331
466 662
503 162
506 073
516 432
523 246
526 325
532 343
546 132
565 703
606 631
612 346
624 632
627 031
631 606
632 624
654 743
662 466
664 311
703 565
712 114
723 431
731 155
732 261
734 371
743 654
754 116

Joe M.

 

[K5MAR]

Joe, just curious, what are these used for? Pretty much everybody in my area uses conventional CTCSS, so I haven't run across anybody using these.

"Inquiring Minds Want To Know!" :lol:

Mark S.

 

[Voyager]

Joe, just curious, what are these used for? Pretty much everybody in my area uses conventional CTCSS, so I haven't run across anybody using these.

"Inquiring Minds Want To Know!" :lol:

Mark S.

Usually, they are used to avoid CTCSS reuse, or band opening problems. There are 50 possible tones (38 standard ones), while there are 104 CDCSS codes.

I'm surprised nobody in your area uses any. Even on business band? That's where they are most popular due to the high number of co-channel users.

Joe M.

 

[INDY72]

Where I live its a nice mix of both CTCSS, and CDCSS tones in usage just for public safety. In the business its even more evenly divided.

Most of the newer systems coming online with narrowband freqs are using mostly CDCSS, with only a few using CTCSS on the new freqs. I have also noticed that the systems using CTCSS are more than likely to use VI scrambling, whereas the CDCSS ones more often use encryption. Of course there are a few exceptions.

 

[unitcharlie]

so how do i know i have an inverted code.... will my pro 96 decode it and display it or do i have to figure it out?

 

[Voyager]

so how do i know i have an inverted code.... will my pro 96 decode it and display it or do i have to figure it out?

Your PRO-96 will NEVER show an inverted code. This only applies to land mobile radio programming, and info obtained from same. Your PRO-96 will always display the non-inverted code, even in the radios are programmed with the inverted code.

If you're looking at an inverted code on a web page, they usually have an i in front of them, like I023.

Joe M.

 

[K5MAR]

Usually, they are used to avoid CTCSS reuse, or band opening problems. There are 50 possible tones (38 standard ones), while there are 104 CDCSS codes.

I'm surprised nobody in your area uses any. Even on business band? That's where they are most popular due to the high number of co-channel users.

Joe M.

There is some DCS, not much. The amazing thing is that some of the agencies that share the same freq will even use the same CTCSS code. For example, even though there is no interoperability issue (one is a PD dispatch, the other is a FD dispatch about 30 miles away on VHF-high), both agencies are using the same CTCSS tone!

Now, business-wise, there just isn't that much activity in my area, and I've don't bother with businesses in the major metro areas (Tulsa/Okla. City) as they are both far enough away (45-55 miles) that they are of no interest to me.

So, no, as far as I know, there are no inverted DCS users in my area.

Mark S.

 

[grem467]

its entirely possible they are using an inverted DPL and your scanner is decoding it as the non-inverted counterpart.

 

[K5MAR]

its entirely possible they are using an inverted DPL and your scanner is decoding it as the non-inverted counterpart.

No, they are both using CTCSS, not DCS. Both my Pro-2067 and my BC780 display 110.9 CTCSS. No DCS displayed.

Mark S.

 

[INDY72]

Of course its entirely up to the local coordinators, and system engineers to decide whether to use CTCSS, or use CDCSS, and to find a suitable tone that doesn't interfere with other locals etc.

 

[scanfan03]

Joe, I never really got this inverted stuff for DPLs, aren't there some for PL's to? My scanner shows that the VFD that I listen to has a DPL of D143, does that mean the radios for the VFD are going to have the inverted DPL programmed into them?

 

[Voyager]

Joe, I never really got this inverted stuff for DPLs, aren't there some for PL's to? My scanner shows that the VFD that I listen to has a DPL of D143, does that mean the radios for the VFD are going to have the inverted DPL programmed into them?

First, there are no inverted CTCSS codes. CTCSS is a sine wave, not a digital code. If you invert a sine wave, you end up with a sine wave of the same frequency just shifted in time 180 degrees.

It's possible SOME radios are programmed with D143, and others are programmed with I412. Maybe all the radios are programmed with I412. You have no way of knowing unless you actually look at the programming.

Inverted CDCSS came about due to the injection (high vs low) of the receiver. With voice or CTCSS, if the pattern is 'upside down', you would never know the difference. It sounds the same to both you and the decoder.

With CDCSS, however, the code will appear normal on one receiver and INVERTED on the other (assuming one has high injection and the other has low injection). There had to be a way to deal with this fact, and inverted CDCSS came about. IF the receiver does invert the code by design, you just program the receiver for the inverted code, and the two inversions cancel each other out. So, the TX may be programmed with D143, and the receiver could be programmed with 412 (the inverted code) in order to work correctly. Since the conversion is not easy, it was more simply to have an 'inverted' code so the TX can be programmed with D143 and the RX can be programmed with I143 to compensate for the receiver design.

I hope this wasn't too complicated to follow.

BTW, in high injection, the local oscillator is running at the I.F. frequency ABOVE the receive frequency. In low injection, the local oscillator is running at the I.F. frequency BELOW the receive frequency. Both types exist, and work the same, except for the fact that the high injection inverts the signal relative to the actual frequency domain.

To make it simple, think of a bouncing ball, and looking at it from below and above. To the person below, it gets farther away at its high point. To the person looking from above (high injection) the ball is closest when it's at its high point. Measuring the distance from the two perspectives, they will be inverted. Only a bouncing ball is a sine wave. Now, put the ball in the digital domain where it is either at its high point or its low point only.

Joe M.

 

[scanfan03]

I get the ball analogy, now, will a radio tell you if it uses Inverted DPLs or not? I've never programmed a radio before, just a lot of scanners.

 

[sadams]

I got one for ya, Voyager: I've got a "non-standard" CDCSS of 711. However, I notice in the program of the radio, it's inverted. So what's the complement code of I711?

 

[ka3jjz]

Voyager - so I can fix this in the wiki - are the left codes the standard, and the right inverted or vice versa?

thanks for the chart...73 Mike

 

[nd5y]

DPL / DCS Information

 

[Thayne]

One reason that some agencies that have been around a long time like to use the same CTCSS tones is that in the old days the "elements ' or reeds needed to generate them were expensive so they just tried to stock as few different ones as possible. But now it is all done by chips already in the radios that are programmed very easily to whatever you want.

 

[N9JIG]

CARMA has a listing of these (with the codes Motorola doesn't include in their mobiles and portables) at

http://www.carmachicago.com/profiles/DPLCODES.pdf

This was produced a few years ago due to a similar query.

Enjoy!

 

[Voyager]

I got one for ya, Voyager: I've got a "non-standard" CDCSS of 711. However, I notice in the program of the radio, it's inverted. So what's the complement code of I711?

Talk about coincidence! I just checked this thread, and I see your reply from yesterday. Anyway...

You have the code of 412, which is the same as code 711 (just shifted in bits). Thus, the inversion is 143.

There are many codes which are the same, only shifted in time. That's why there are only 104 standard codes, and not 888. To demonstrate this, a code of 0010 and 0100 would be the same if they were sent continuously. CDCSS codes are much longer than that, but it's the same concept.

Joe M.

 

[Voyager]

Voyager - so I can fix this in the wiki - are the left codes the standard, and the right inverted or vice versa?

thanks for the chart...73 Mike

As stated in the original reply, they are mutually exclusive. The left column can be the standard, which makes the right inverted, or the left can be inverted which makes the right standard.

Joe M.