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Quiver

1030 modem adventures

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So I decided to drag out the 1030 from storage to see if I can connect to the Linux server in my house over a VoIP connection. The answer is yes, but not to be trusted for data transfers. I have a couple of DAHDI cards ordered to see if I can improve on that. However I had an issue crop up with tone dialing, my ATA stopped recognizing the tones. So I dialed the PC modem with the phone handset connected to the 1030 then pressed 'F' on Bobterm, and it connected. So the ATA seemed to be fine then. I then listened on the phone handset while the Atari dialed, and heard a curious thing. There was what almost sounded like a recording prompt tone, the low and almost bell like kind followed by DTMF tones with an audio glitch of the previous sound. I'm sure this is what is causing the ATA from recognizing the tones and causing a dialing failure.

Now the question before I open the modem up is: should I expect this to be an issue caused by bad caps, or some other part?

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The 1030, and it's descendant the XM301, send DTMF tones by amplifying audio from the SIO audio *IN* port, which was never originally intended to send audio *OUT". The DTMF tones are 4-bit approximations of the wave forms played by the pokey using amplitude mode - so it would be quite understandable to pick up a lot of noise from the Atari. It was barely enough to get past regulation apparently!

 

I've also been delving into DIY VoIP ATA's recently, and have currently got a configuration that seems to hold a stable v.34 28800 connection using g.711u, a small fixed jitter buffer, no echo cancellation and no fax tone detection. it's a grandstream HT802 with 2 FXS ports, so I think I should be golden to dial between the two "extensions" using some fun combinations of 300-1200bps modems - 830, 1030, XM301, MPP, SX212, etc. :)

 

Will have to see how well this one can handle the funky 1030/XM301 DTMF - worst case this ATA has a setting I can enable for pulse dialing, so might have to resort to that... or just manually dial as is needed for the 830 hehe.

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Something I'm not totally clear on follows; if you could clarify, it would be appreciated.

 

1 hour ago, Quiver said:

However I had an issue crop up with tone dialing, my ATA stopped recognizing the tones. So I dialed the PC modem with the phone handset connected to the 1030 then pressed 'F' on Bobterm, and it connected. So the ATA seemed to be fine then.

 

Does this mean that in this case you're calling purely internally (i.e., extension-to-extension) via your Asterisk server?  I think I can kind-of picture your setup (1030 on one extension, PC with modem on another), but am not 100% certain that's correct.

 

Is any of the household phone wiring used to make this connection?  It's possible that you've got a run (likely to the 1030) that has line noise on it where others don't.  It's rare for it to be that localised of a problem, but it can happen.

 

I've been running an on-again, off-again (off right now while I get around to completely migrating it to a new platform) VoIP-based dialup BBS.  It's using a Trendnet TFM-561U 56Kbps USB modem to pull back to an FXS port on an Obihai 202.  The Obihai a) acts as a Google Voice adapter, and b) trunks that Google Voice line back to the local Asterisk box so that I have more control over that line than the Obihai by itself allows.  The same Asterisk box / Google Voice combination also handles faxes.

 

I've been using this method for close to 4 years on data and more like 6 or 7 for fax, and haven't run into any issues.  VoIP isn't ideal for trying to do in-band data, but I can get consistent 9600bps speeds for both data and fax over the VoIP lines, so 300bps should be easily achieveable in your case.

 

Late edit: looks like @Nezgar posted while I was writing this.  Definitely check into the SIO / DTMF / Pokey issue he mentioned.  I don't have any Atari modem hardware here, so can't do a direct comparison test against the other modems I do have.

Edited by x=usr(1536)

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Yes, it's 1030 on one extension, and PC modem on the other. I certainly need to do some tuning to improve reliability, it's fairly solid, but not solid enough. The issue though, is the fact that the DTMF from the 1030 is too deficient to be recognized by the ATA now. It was working great the previous day.

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Just now, Quiver said:

 DTMF from the 1030 is too deficient to be recognized by the ATA now. It was working great the previous day.

Once the terminal software is booted, try removing absolutely everything from the SIO chain except the 1030. It has to amplify a very weak audio signal from the computer, so maybe this will minimize any signal loss...

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Interesting, I may have to look into a setup like this as I have a 1030. I'm pretty sure the last time I tested Altirra's replacement 1030 handler that I was able to tone dial out over a landline and actually connect to Earthlink at 300 baud.

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Not to mention that most modems put out just above the minimum level of signal necessary to get the data onto the wire and tend to let the telco worry about the rest.  If, as hypothesised, there's a cap issue (or voltage) with the 1030, that could really screw with things.

 

Something could also have crapped out in the ATA, though my money's still (mostly) on the 1030.  Definitely interested to see what happens when the DAHDI cards arrive, however.  That's something I've been considering moving to in lieu of directly connecting POTS equipment to the Obihai devices.

Edited by x=usr(1536)

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So I isolated the modem on the SIO chain. Unusual tone removed, tone dialing still not recognized by the ATA. The source of the tone was from the SIO2PC electronics. Very strange as there is no connection to audio in the SIO2PC. I'm suspecting that the tones might not be loud enough. It looks like I may need to crack it open and check components. ATA is not at fault as a regular phone dials just fine. I added the same tuning that Nezgar used for jitter. Much improved reliability.

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1030 schematic and spec sheets for the TMS99532 (modem IC) and LM324 (op-amp, location U5D) attached.

 

If I'm reading everything correctly, DTMF audio flow from the POKEY to the 1030 goes like this: SIO pin 11 out to the LM324 at U5D to TMS99532 pin 17.  From there, it's output over pin 16 of the TMS99532, but I'm going to deliberately ignore that entire stage for now.

 

Pin 17 on the TMS99532 is a general analogue input pin, so it makes sense that the LM324 at U5D is tied to it.  The LM324 is basically operating as a pre-amp for the weak audio coming from the SIO port before that audio hits the TMS99532.  That audio needs to be suitably-amplified before being sent to the TMS99532, so, if it isn't, it'll be passed weak and/or distorted on down the line.  This has me wondering if the LM324 at U5D isn't flaky.

 

There are two more op-amps on the output side at U6A and U6C, but for now it's probably worth seeing what you're getting in the way of input before looking at that side of things.

 

BTW: which model of machine are you using?  I just checked the thread and couldn't find any mention of it.

 

Late edit: from re-reading the schematic, there may only be one LM324 op-amp on the board.  Can't verify that without a picture of the board or a 1030 in hand, though.

 

1030.jpg

TXIIS145563-1.pdf LM324-D.PDF

Edited by x=usr(1536)

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Another thought: the POKEY could be going south, or there could be an issue with pin 11 on the SIO connectors or cable between the Atari and the 1030.  Grasping at straws here, but given that POKEY is integral to dialling, those are other items in the chain that might be worth investigating.

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I'm currently using an 800XL with a U1MB. It and an 800 with 48k was our family's first computers. I remember dad getting them, a 1050, 410, and this 1030 in trade for a pest control job, as well as all the software, cartridges, and many copies of Antic magazine. Quite a bit of the software was pirated, but most was not. Our family's next computer sadly was not an Atari but a 386DX by a company called PCpositive.

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50 minutes ago, Quiver said:

I'm currently using an 800XL with a U1MB.

 

OK, good to know.  I'm guessing that the 1030 was always working with the U1MB installed (i.e., problems with the 1030 started after the U1MB was installed).

 

In no particular order, some things you may want to try:

  • Make sure that the POKEY is working right, not getting overly-hot, etc.  Don't trust the self-test for this; use something (insert demo disk here) that will really pound on it, and continuously.
  • May want to go through the pain of removing the U1MB and running the 1030 from the XL in bone-stock state.  One thing I can think of off the top of my head: the U1MB may be overdrawing the XL's PSU, especially if it's a prone-to-failure factory PSU.  Not totally convinced of this theory, but it would eliminate at least one variable - peripherals like these were never intended to work with modern (or any, really) upgrades.
  • Swap out the SIO cable between the XL and the 1030 with one that's known-good and see what happens.  Check pin 11 for continuity at each end on the one currently in that position.

 

Regardless, it sounds like you're probably going to need to open up the 1030, XL, or possibly both and do some investigation.

 

Dumb question, since I'm not sure which ATA you're using: does it also have at least two RJ-11 jacks on it, and can they act as standard POTS extensions where picking up a phone in one room allows you to hear what's being said on the phone in the other room?

 

If so, I'd be interested to find out what the ATA is hearing when the 1030 dials.  Basically, plug your POTS handset into the RJ-11 jack and listen in to the 1030 dialling.  Same thing as was done on the modem, just on the ATA side.

 

Edited by x=usr(1536)

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Sadly I don't have an ATA like that. I'm using a Walmart basictalk that I flashed the firmware to to be the Grandstream ht701 that it actually is. Hopefully I won't need to remove the U1MB. I'm afraid the original MMU didn't survive the upgrade. I'll start with the modem first, as the audio system of this model was close to being a complete kludge, and would be the most likely place of failure.

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29 minutes ago, Quiver said:

Sadly I don't have an ATA like that. I'm using a Walmart basictalk that I flashed the firmware to to be the Grandstream ht701 that it actually is.

Ah.  I didn't realise it was one of those.

 

I've replaced about a dozen of them with completely different units for various clients over the past several years.  They are not what I would call a well-built device.

Quote

Hopefully I won't need to remove the U1MB. I'm afraid the original MMU didn't survive the upgrade. I'll start with the modem first, as the audio system of this model was close to being a complete kludge, and would be the most likely place of failure.

Hold off until your DAHDI card arrives.  If connecting the 1030 to that fixes the problem, awesome.  If not, we can pick up on troubleshooting from there, but that HT701 needs to be ruled out.  Right now, though, it's hard to pin down an exact cause.

Edited by x=usr(1536)

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I do happen to have an analog PBX that arrived yesterday. I was planning on possibly doing a video on budget friendly methods on using vintage modem gear. I can try getting that running with the modems.

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3 hours ago, x=usr(1536) said:

I'd be interested to find out what the ATA is hearing when the 1030 dials.  Basically, plug your POTS handset into the RJ-11 jack and listen in to the 1030 dialling. 

Plug the 1030 into the ATA using the cord hanging out of it, and plug a phone into the jack in the 1030. Then listen to the loudness of the DTMF tones on the phone as it dials, and see if you can tell any difference in the loudness comparing with another newer modem that can dial itself.

 

3 hours ago, Quiver said:

Grandstream ht701

Hmm. Wonder how the older HT701 does compared to a newer HT801. Also, my 801 has an option to enable pulse dialing (disabled by default), I think that setting was also available in the 701?

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Okay, I had a real tech support moment, which is kinda like a senior moment, but features forgetting about the glaringly obvious in regards to tech.

 

So, I connected the modems together using the PABX that I had gotten a couple of days ago. DTMF from the 1030 was still not recognized. So it was looking pretty grim for the 1030 with exploratory surgery all but scheduled. I then reconnected everything back to the HT701's and swapped out the 800XL for a 65XE. Tone dial worked. Now things are looking grim for the 800XL with the prospect of surgical exploration. I swapped the 800XL back in, and tone dialing worked. Now here's the tech support moment: I never restated the SIO cable at the 800XL itself, only the end connecting to the modem. I must apologize for involving everyone in a problem that could have been fixed with the most basic of tech support procedures.

 

Thank you for your help everyone.

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1 hour ago, Quiver said:

Okay, I had a real tech support moment, which is kinda like a senior moment, but features forgetting about the glaringly obvious in regards to tech.

 

So, I connected the modems together using the PABX that I had gotten a couple of days ago. DTMF from the 1030 was still not recognized. So it was looking pretty grim for the 1030 with exploratory surgery all but scheduled. I then reconnected everything back to the HT701's and swapped out the 800XL for a 65XE. Tone dial worked. Now things are looking grim for the 800XL with the prospect of surgical exploration. I swapped the 800XL back in, and tone dialing worked. Now here's the tech support moment: I never restated the SIO cable at the 800XL itself, only the end connecting to the modem. I must apologize for involving everyone in a problem that could have been fixed with the most basic of tech support procedures.

 

Thank you for your help everyone.

No worries, we've all been there.  At least it was an easy fix.

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