NEXEDGE48 and DSD+ Set-Up Help

Hi all. I'm having many problems setting up a network that I've been trying to get to work for several weeks now, but it doesn't seem to be working. It is NOT listed in the RR database, so trying to find all the sites, frequencies on my own. I'm totally stumped now and don't know what else to try. I'm using 2 RTL-SDR USB dongles, and DSD+ 1p114.

From the FCC database, Callsign WSG635 is the only thing listed for the particular frequencies of 451.5 and 451.8625 and that's what I'm going with. I found those 2 frequencies in SDRSharp and they are both associated with Network L32 (whatever the L stands for?). I put all frequencies listed for that system into my frequencies file, using the Loc# as the Site number and the Freq ID# as the OTAChannelNumber. I know that's wrong, but it's a start. Here's my DSDplus.frequencies file:

NEXEDGE48, 32, 0, 1, 461.2000, 461.2000, 0
NEXEDGE48, 32, 0, 1, 461.2000, 461.2000, 0
NEXEDGE48, 32, 0, 2, 461.6000, 461.6000, 0
NEXEDGE48, 32, 0, 3, 463.5500, 463.5500, 0
NEXEDGE48, 32, 0, 1, 461.2000, 461.2000, 0
NEXEDGE48, 32, 0, 2, 461.6000, 461.6000, 0
NEXEDGE48, 32, 0, 3, 461.2000, 461.2000, 0
NEXEDGE48, 32, 0, 4, 463.5500, 463.5500, 0
NEXEDGE48, 32, 0, 5, 468.5500, 468.5500, 0
NEXEDGE48, 32, 0, 1, 451.4000, 451.4000, 0
NEXEDGE48, 32, 0, 2, 451.8625, 451.8625, 0
NEXEDGE48, 32, 0, 3, 452.0125, 452.0125, 0
NEXEDGE48, 32, 0, 4, 461.8500, 461.8500, 0
NEXEDGE48, 32, 0, 5, 462.1500, 462.1500, 0
NEXEDGE48, 32, 0, 6, 461.4000, 461.4000, 0
NEXEDGE48, 32, 0, 7, 463.3750, 463.3750, 0
NEXEDGE48, 32, 0, 1, 451.3000, 451.3000, 0
NEXEDGE48, 32, 0, 2, 451.3500, 451.3500, 0
NEXEDGE48, 32, 0, 3, 452.6750, 452.6750, 0
NEXEDGE48, 32, 0, 4, 453.0000, 453.0000, 0
NEXEDGE48, 32, 0, 5, 461.6000, 461.6000, 0
NEXEDGE48, 32, 0, 6, 461.1750, 461.1750, 0
NEXEDGE48, 32, 0, 7, 451.5000, 451.5000, 0
NEXEDGE48, 32, 0, 8, 452.7250, 452.7250, 0
NEXEDGE48, 32, 0, 9, 451.8250, 451.8250, 0
NEXEDGE48, 32, 0, 10, 451.8750, 451.8750, 0
NEXEDGE48, 32, 0, 11, 451.9000, 451.9000, 0
NEXEDGE48, 32, 0, 12, 452.0500, 452.0500, 0
NEXEDGE48, 32, 0, 13, 452.1000, 452.1000, 0
NEXEDGE48, 32, 0, 14, 452.2000, 452.2000, 0
NEXEDGE48, 32, 0, 15, 452.5000, 452.5000, 0
NEXEDGE48, 32, 0, 16, 452.7500, 452.7500, 0
NEXEDGE48, 32, 0, 17, 461.0500, 461.0500, 0
NEXEDGE48, 32, 0, 18, 452.7000, 452.7000, 0
NEXEDGE48, 32, 0, 1, 456.4000, 456.4000, 0
NEXEDGE48, 32, 0, 2, 456.8625, 456.8625, 0
NEXEDGE48, 32, 0, 3, 457.0125, 457.0125, 0
NEXEDGE48, 32, 0, 4, 461.8500, 461.8500, 0
NEXEDGE48, 32, 0, 5, 462.1500, 462.1500, 0
NEXEDGE48, 32, 0, 6, 461.4000, 461.4000, 0
NEXEDGE48, 32, 0, 7, 463.3750, 463.3750, 0
NEXEDGE48, 32, 0, 8, 466.8500, 466.8500, 0
NEXEDGE48, 32, 0, 9, 467.1500, 467.1500, 0
NEXEDGE48, 32, 0, 10, 456.4000, 466.4000, 0
NEXEDGE48, 32, 0, 11, 468.3750, 468.3750, 0


Ok, now my FMP-CC.bat file:
FMP24 -i1 -o20001 -P53.0 -f451.5

My CC.bat file:
DSDPlus -rc -i20001 -v3 -wsl400.2 -wss100.200 -wel0.1 -wcl0.445 -wes400.520 >>CC.log

A snippet from my CC.log file:
DSD+ 1.114pt
Program role is control/rest channel decoder
Source audio waveform window origin set to (400,2)
Source audio waveform window dimensions set to 100x200
Event log window origin set to (0,1)
Channel window origin set to (0,445)
Event log window dimensions set to 400x520
Appending synthesized audio to file 'CC-DSDPlus.wav'
58 frequency records loaded
347 radio records loaded
21 group records loaded
0 site records loaded
0 network records loaded


Initiating TCP connection to 127.0.0.1:20001...
Connected to 127.0.0.1:20001
audio output device #1 = 'Speakers (Realtek High Definiti'
audio output device #2 = 'Realtek Digital Output (Realtek'
audio output device #3 = 'CABLE Input (VB-Audio Virtual C'
audio output device #4 = 'LCD TV-4 (NVIDIA High Definitio'

audio output device #1 (Speakers (Realtek High Definiti) initialized

D-STAR decoding enabled
NXDN4800 decoding enabled
NXDN9600 decoding enabled
DMR/MotoTRBO decoding enabled
P25 Phase 1 decoding enabled
X2-TDMA decoding enabled
ProVoice decoding enabled
Sync:+NXDN48 TB CCDATA ERR32
Sync:+NXDN48 TB CCDATA ERR12 SRV_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl
Sync:+NXDN48 TB CCDATA ERR35
Sync:+NXDN48 TB CCDATA ERR1 SRV_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl
Sync:+NXDN48 TB CCDATA ERR13 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR2 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR2 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR17 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR1 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR1 SITE_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl Version=1 Neighbors=4 CC=93
Sync:+NXDN48 TB CCDATA ERR2 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR5 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR31
Sync:+NXDN48 TB CCDATA ERR2 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR33
Sync:+NXDN48 TB CCDATA ERR17
Sync:+NXDN48 TB CCDATA ERR33
Sync:+NXDN48 TB CCDATA ERR1 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR5 SRV_INFO
Sync:+NXDN48 TB CCDATA SRV_INFO
Sync:+NXDN48 TB CCDATA ERR3 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR32
Sync:+NXDN48 TB CCDATA ERR10 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR29
Sync:+NXDN48 TB CCDATA ERR33
Sync:+NXDN48 TB CCDATA ERR30
Sync:+NXDN48 TB CCDATA ERR30
Sync:+NXDN48 TB CCDATA ERR32
Sync:+NXDN48 TB CCDATA ERR4 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR28
Sync:+NXDN48 TB CCDATA ERR29
Sync:+NXDN48 TB CCDATA ERR33
Sync:+NXDN48 TB CCDATA ERR9 SITE_INFO
Sync:+NXDN48 TB CCDATA ERR31
Sync:+NXDN48 TB CCDATA ERR33
Sync:+NXDN48 TB CCDATA ERR34
Sync:+NXDN48 TB CCDATA ERR5 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR32
Sync:+NXDN48 TB CCDATA SRV_INFO
Sync:+NXDN48 TB CCDATA ERR30
Sync:+NXDN48 TB CCDATA ERR2 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR30
Sync:+NXDN48 TB CCDATA ERR9 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR6 SRV_INFO
Sync:+NXDN48 TB CCDATA ERR33

And my CC-DSDPlus.event file:
2016/03/13 15:41:01 DSD+ 1.114pt / Fast Lane Release
2016/03/13 15:41:01 [Name and Email Removed]
2016/03/13 15:41:01 D-STAR decoding enabled
2016/03/13 15:41:01 NXDN4800 decoding enabled
2016/03/13 15:41:01 NXDN9600 decoding enabled
2016/03/13 15:41:01 DMR/MotoTRBO decoding enabled
2016/03/13 15:41:01 P25 Phase 1 decoding enabled
2016/03/13 15:41:01 X2-TDMA decoding enabled
2016/03/13 15:41:01 ProVoice decoding enabled
2016/03/13 15:41:01 Current network: L32
2016/03/13 15:41:01 Current site: L32-4
2016/03/13 16:07:06 L32-4 neighbor: Site L32-2; CC=510
2016/03/13 16:07:06 L32-4 neighbor: Site L32-3; CC=462


When I run both bat's, I get:
NEXEDGE48 Site:L32-4 RAN:4 NL:2 3 5 -

I understand that the L32-4 is System ID 32 and Site 4, what's up with the L?
What is RAN stand for?
I think NL is a neighbor list, with sites 2, 3, and 5 neighbors, but what about the "-"? (dash)

In the CC Channel Activity window, I get 93 under "Ch" and CC under "Target".
I just now got a 685 pop up under the "Ch" heading also.


I believe I should be getting more activity than this, any help in pointing me where to go next would be appreciated. Thanks so much!

kh6sz said:

I understand that the L32-4 is System ID 32 and Site 4, what's up with the L?

Click to expand...

NEXEDGE systems broadcast a two bit category value - Global, Regional or Local.

What is RAN stand for?

Click to expand...

It's their version of an access code, similar to CTCSS/DCS.

I think NL is a neighbor list, with sites 2, 3, and 5 neighbors, but what about the "-"? (dash)

Click to expand...

Sync:+NXDN48 TB CCDATA ERR1 SITE_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl Version=1 Neighbors=4 CC=93

Your decode rate is so bad that you haven't picked up the fourth site, despite that information being sent repeatedly.

In the CC Channel Activity window, I get 93 under "Ch" and CC under "Target".
I just now got a 685 pop up under the "Ch" heading also.


I believe I should be getting more activity than this, any help in pointing me where to go next would be appreciated. Thanks so much!

Click to expand...

I would start by cleaning up the signal. Better location, better antenna(s), get more centered on frequency - something...

If you can't decode the neighbour list, you're not going to decode very many voice call assignments.

I agree with Slicerwizard, in order to get a decode you need a strong clean signal. By looking at the RAW Data, there are errors on every line. If you have a strong signal then you are getting interference. This could be from a electrical source or a nearby transmitter.

ScanWI said:

I agree with Slicerwizard, in order to get a decode you need a strong clean signal. By looking at the RAW Data, there are errors on every line. If you have a strong signal then you are getting interference. This could be from a electrical source or a nearby transmitter.

Click to expand...

Ok, I moved the antenna about a foot, and now I get a much better signal, still throws an err or to every now and then, but much better than before. Looking thru the logs, I found this line and was wondering if someone can translate it for me to exactly what it's saying.

Sync:+NXDN48 TB CCDATA ADJ_SITE_INFO Neighbor L32-2 CC=510 2 Neighbors; L32-3 CC=462 3 Neighbors; L32-5 CC=620 4 Neighbors

Remember, the CC Even Log window shows NEXEDGE48 SiteL32-4 RAN:4 NL:2 3 5 -

Is CC for the Control Channel, Color Code, or Channel Number?
If it's the channel number, I should be able to run them thru the formula and figure out the frequencies, right?

How are the neighbors calculated? Is there a way to know for sure which sites the 2, 3, or 4 neightbors are? Would Site 2 only have 2 frequencies, Site 3 have 3 frequencies, and Site 5 have 4 freqs?

Sorry for all the questions, but I'm doing my best to understand that everything means. Here's some other snippets from the log:

Sync:+NXDN48 TB CCDATA SRV_INFO
Sync:+NXDN48 TB CCDATA SRV_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl
Sync:+NXDN48 TB CCDATA SRV_INFO
Sync:+NXDN48 TB CCDATA SRV_INFO

Sync:+NXDN48 TB CCDATA SRV_INFO
Sync:+NXDN48 TB CCDATA SITE_INFO Category=Local System=32 Site=4 MultiSite LocnReg GrpReg Voice Data ShortData Status&RemCtl Version=1 Neighbors=4 CC=93
Sync:+NXDN48 TB CCDATA SRV_INFO

P.S. Does the DSDPlus.frequencies file have anything to do with what is being displayed?

Thanks for all the Help!

We are hear to answer your questions.

in this case CC stands for Control Channel
Sync:+NXDN48 TB CCDATA ADJ_SITE_INFO Neighbor L32-2 Neighbors; L32-3 CC=462 3 Neighbors; L32-5 CC=620

NexEdge 4800 Baud - uses 6.25Khz bandwidth
System ID - 32
Control Channel on site 2 is Channel number 510
Control Channel on site 3 is Channel number 462
Control Channel on site 5 is Channel number 620

These is no set formula for the channels, some systems have generated the channels automatically based on a base frequency. Once you figure out 2 or 3 of the frequencies and what channel number they correspond to you can figure out how they set up their table. One of the systems in my area has a channel table that does not follow any pattern and the other large system is based off of 6.25 steps from 450-455 and 460-465. I have a spreadsheet that has a basic channel table mapped out that I could send you. you could then plug in your frequencies and see if it matches up.

Any site can have any number of frequencies/repeaters. Without knowing the frequencies and eiher looking upt eh license or driving to find the strongest signal there is no way to know for sure where the other sites are.

The Neighbor list is programmed into the system by the owner, it is a list that is in the control Channel data so that the radios know what other sites to look for when roaming. This allows the radios to roam without the operator telling the radio to. This list is will is completely dependent on programming on the system. Typically any tower that is near the tower you are listening to will be in this list, and this list will be different on each tower based on location.

Does the DSDPlus.frequencies file have anything to do with what is being displayed?

Click to expand...

This file is used for trunk tracking the NXDN and DMR systems, this file must be populated by you as the user.

Here is a snippet of how part of my Frequencies file looks. You just need to follow the format indicated.

Example of the first entry
protocol=NEXEDGE96
networkID=57
siteNumber=2
OTAchannelNumber=333
TXfrequency=454.0750
RXfrequency=454.0750
sortOrder=0

; line format:
;
; protocol, networkID, siteNumber, OTAchannelNumber, TXfrequency, RXfrequency, sortOrder

NEXEDGE96, 57, 2, 333, 454.0750, 454.0750, 0
NEXEDGE96, 57, 3, 374, 454.33125, 454.33125, 0
NEXEDGE96, 57, 3, 375, 454.3375, 454.3375, 0
NEXEDGE96, 57, 4, 373, 454.3250, 454.3250, 0

Click to expand...

You can use two SDR dongles, that can be purchased for $20, or a scanner and a Dongle to track these systems. with this setup you can hold, lockout, and set priorities on the talkgroups much like you can on a scanner.

Some companies may start the calculation based off of a different channel. Once this is figured out it makes finding the system frequencies much easier. There is no standard for how this calculation is done. it can be in 6.25, 3.125, 12.5, 25 steps, I have seen all of these at times in channel tables.

If you want to make your own table;
1-Open Microsoft Excel or OpenOffice Calc
2-Type in 450.0000 in the first cell
3-Type in 450.0625 in the row below the first
4-Highlight both cells
5-Move you cursor to the bottom right corner of the bottom cell until you see a plus sign
6-Click and drag the highlight down the sheet
7-Release the mouse and Excell/Calc will fill in the frequencies based on the step between the first two
8-After you have done this in Column B put a 1 in row 1 and 2 in row 2
9-Highlight and drag these numbers like you did in Step 4-7

Note - You can use any frequencies for the first two entries but they need to be adjacent channel numbers int eh official Channel table.
Example - Ch 1 and 2 ---- Ch 321 and 322 ---- using Ch1 and Ch 20 will not work

In order to calculate if you do have Ch 1 and Ch 20
Ch 1 = 452.250
Ch 20 = 453.4375

There are 19 steps between the two channels, so we just need to figure out what step size fits into the 19 spots.
-If it is a 4800 baud system it will most likely be 6.25. So if you take 453.4375-452.250=1.1875
-1.1875 is the frequency space between these two channels
-Now divide 1.1875 by 19 to get .0625
-This gives us the step which is the key to figuring out the channel table.
-So if we add .0625 to one of the channels
-Then use the process above we will be able to create a channel table

After you have done this in Column B put a 1 in row 1 and 2 in row 2

From looking at the locations on the fcc license, it looks like your closer to Pass Christian Ms. I could be wrong. But if Pass Christian is closer to you, just focus on the freqs listed for them.

If you have a scanner, put the freqs below in and see if you hear any digital noise. If you have one freq thats constant, thats most likely the control channel (CC). You mentioned 451.8625 and thats listed under Pass Christian

451.4000 451.8625 452.0125 461.4000 461.8500 462.1500 463.3750

If your closer to any of the other locations listed on their license, do whats mentioned above.

Or put all the freqs in that are on the license and scan them,

When you find the closest control channel to you, edit your FMP-CC.bat to have it scan the cc.
Mine looks like this. FMP -i1 -o20001 -P77.0 -f461.6940 , so on yours you put the cc where i have 461.6940.


Now if you launch FMP-CC.bat, and then CC.bat, you will see the cc activity window. With that running, and watching the freqs your scanner is scanning, you could most likely figure out the over the air (ota) and write them down.

ScanWI said:

Some companies may start the calculation based off of a different channel. Once this is figured out it makes finding the system frequencies much easier. There is no standard for how this calculation is done. it can be in 6.25, 3.125, 12.5, 25 steps, I have seen all of these at times in channel tables.

If you want to make your own table;
1-Open Microsoft Excel or OpenOffice Calc
2-Type in 450.0000 in the first cell
3-Type in 450.0625 in the row below the first
4-Highlight both cells
5-Move you cursor to the bottom right corner of the bottom cell until you see a plus sign
6-Click and drag the highlight down the sheet
7-Release the mouse and Excell/Calc will fill in the frequencies based on the step between the first two
8-After you have done this in Column B put a 1 in row 1 and 2 in row 2
9-Highlight and drag these numbers like you did in Step 4-7

Note - You can use any frequencies for the first two entries but they need to be adjacent channel numbers int eh official Channel table.
Example - Ch 1 and 2 ---- Ch 321 and 322 ---- using Ch1 and Ch 20 will not work

In order to calculate if you do have Ch 1 and Ch 20
Ch 1 = 452.250
Ch 20 = 453.4375

There are 19 steps between the two channels, so we just need to figure out what step size fits into the 19 spots.
-If it is a 4800 baud system it will most likely be 6.25. So if you take 453.4375-452.250=1.1875
-1.1875 is the frequency space between these two channels
-Now divide 1.1875 by 19 to get .0625
-This gives us the step which is the key to figuring out the channel table.
-So if we add .0625 to one of the channels
-Then use the process above we will be able to create a channel table

After you have done this in Column B put a 1 in row 1 and 2 in row 2

Click to expand...

Thank you ScanWI:
My frequencies that I got are different from the list you sent. Here's what I found so far. The control channels are Ch 93 (451.5) and Ch 151 (451.8625). From those 2 channels, going thru the logs, I've found Ch 510 Site 2 (461.3625), Ch 462 Site 3 (460.7625), Ch 620 Site 5 (462.7375), Ch 562 Site 2 (457.0125), Ch 518 Site 3 (461.4625), and Ch 738 Site 5 (464.2125). The Channel and Sites were given and I used the formula I found to get the Frequencies, which seem to work.

Then, Ch 978 popped up on my CC Activity window with activity, but couldn't hear anything. So I tried the formula, modified to my best guess (didn't work) to get 472.2125. Nothing. So I used one SDR dongle to keep the control channel active and use SDR# to scan from 450.0000 up, and found the frequency that pops up everytime Channel 978 keyed up, which was 464.7125. All channels I've received so far are encrypted, but still I'm working on it to learn about how this stuff works.

Ok, I think I may have identified part of my problem with finding all the frequencies. I have 3 frequency/channel pairs that I know are correct because of activity in DSD+. They are:

Channel 93 = 451.5
Channel 151 = 451.8625
Channel 978 = 464.7125

I tried the formula that's foound elsewhere on RR, but the numbers don't come out right. Here's the formulas:

Standard UHF Map Formulas
For Channels 1 to 400:
Freq = 450 + (( Ch - 1 ) * 0.0125)

For Channels 401 to 800:
Freq = 460 + (( Ch - 401 ) * 0.0125)

For Channels 801 to 1023
Custom frequency, i.e. T-Band or on a 6.25 KHz step.

As you can see, they don't work correctly:

Freq = 450 + ((93 - 1) * 0.0125 = 451.15 (Not 451.5)
Freq = 450 + ((151 - 1) * 0.0125 = 451.875 (Not 451.8625)

Is there another formula floating around somewhere that will find channels and frequencies that I have not yet found? Thanks!

kh6sz said:

Channel 93 = 451.5
Channel 151 = 451.8625
Channel 978 = 464.7125

Click to expand...

You should be able to figure out the difference in Hz between 451.5 and 451.8625; you should also be able to figure out the difference between 93 and 151. And when you divide the Hz distance by the channel number difference you'll get 6250 Hz (6.25 kHz); so now you know the step size (frequency difference from one OTA channel number to the next. From there, you should be able to figure out the base frequency (frequency for OTA channel zero); with base and step, you can convert any OTA channel number to a frequency.

Unfortunately, the channel numbers don't seem to have to follow any pattern at all, even within a given site. In my area (SoCal), for example, the channels I have so far for site 31-4 are:

214: 454.115625 (CC)
797: 471.175000
807: 471.400000
814: 471.587500
816: 471.600000
824: 471.700000
825: 471.750000
893: 471.225000

The control channel is a 3.125 kHz "split" channel, so that's not going to follow any normal map anyway. 814/816 imply a step of 6.25 kHz per channel, but 816/824 implies 12.5 kHz, 824/825 implies 50 kHz, and 893 is lower than all of them!

These are my known control channels (according to each site) for system 31:

Site 1: Ch 409: 454.621875
Site 3: Ch 358: ?
Site 4: Ch 214: 454.115625
Site 6: Ch 193: 454.015625
Site 7: Ch 908: 507.437500
Site 8: Ch 938: ?
Site 13: Ch 211: 454.034375
Site 25: Ch 833: ?
Site 29: Ch 590: 462.737500

There is no apparent pattern between the sites.

AM909 said:

....Unfortunately, the channel numbers don't seem to have to follow any pattern at all, even within a given site. ....

Click to expand...

Amen!! With some of these systems there is no rhyme or reason to anything, or at least it appears that way. I have become more and more impressed with the P-25 protocol, after messing around with all these other protocols...

This is very true as stated above, the channels do not have to follow any formula. It only works if the people who set up the system followed the formula. When you program the table into the radios you can calculate it automatically or put the channels in at will.

It will be nice when more systems start rolling out Gen2 NXDN, this will do away with the channel numbers and the CC will tell the radios what frequency just like in P25.

The NEXEDGE48 systems I monitor here in NorCal are setup much like the systems AM909 monitors in SoCal. None of the OTA to frequency mappings follow any standard formula. More channel numbers are in the 800's but one system has three in the 50's, one in the 200's and one in the 400's.

The only way I was able to figure out the channel mappings was to use the list of repeater output frequencies from the FCC database and use a trial and error approach to confirm the mappings.