Have others measured their download speed? I only get around 30 kbps versus up to 40 kbps with some of my other modems.

Is there anything I can do to improve this?

By the way, I modifed the driver inf file and have the AT#UD diagnostics now displaying in the WinXP Modemlog.

Thanks, Kent

By limiting the connect speed, I have achieved download rates as high as 36 Kbps with two of my three ISPs. This compares very favorably with my DSP and Controller based modems.

However, with my third ISP I see download rates of only 25-30 Kbps. In some cases I have seen even less. I use the speedtest at speakeasy.net for these tests.

Upload rates are anywhere from 70 to 200 Kbps which must imply that compressed files are transmitted. Does anyone have any other explanations?

By the way, I seem to be getting the best performance from my Diamond Supramax PCI Pro modem with the latest Conexant chip and the latest generic driver from their website.

Things you can also try -
with/without V.92 / V.44 compression (assuming your ISPs support V.92 & V.44);

Connecting modem directly to your demarc, or if not practical, removing all other devices connected to phone line to see if there is any difference
www.modemsite.com/56k/demarc.asp

(My tests on SV92P PCI have given me downloads around 50kbps (already compressed files) - but I'm lucky to have good line/short run to telco and get connect rates of 48k - 52k.

Aloha! Richard.

That 50kbps with an already compressed file sounds terrific. Have you tried any of the internet speedtests such as the one I referenced above? I wonder if these are good benchmarks to use for a 56K modem. The best I have achieved using Speedtest is 41kbps.

Attached below is a diagnostic log on this modem. I eliminated the speed limiting for this run. This SV92PL based modem performs quite a bit better when I limit the speed to something in the area of 41333 bps.

By the way, I use the free Kerio Firewall which includes a little oscilloscope that is great for monitoring the modem performance during a download test. When I see a straight line during download I know the modem is performing very nicely.

11-30-2005 20:08:05.765 - Modem Diagnostics:
11-30-2005 20:08:05.765 - Connect Response: ..CONNECT 50666 V44..
11-30-2005 20:08:05.765 - Version 1.0
11-30-2005 20:08:05.765 - Call Setup Result: Data Calling signal detected
11-30-2005 20:08:05.765 - Multi-media mode: Data Only
11-30-2005 20:08:05.765 - DTE-DCE interface mode: Async data
11-30-2005 20:08:05.765 - Received signal power level (in -dBm): 26
11-30-2005 20:08:05.765 - Transmit signal power level (in -dBm): 13
11-30-2005 20:08:05.765 - Estimated noise level (in -dBm): 73
11-30-2005 20:08:05.765 - Round Trip delay: 11 ms
11-30-2005 20:08:05.765 - Don't know to format (0x00000020, 0x000000ff) for tag 0x2a4d3263
11-30-2005 20:08:05.765 - Transmit Carrier symbol rate: 3200
11-30-2005 20:08:05.765 - Transmit Carrier frequency: 1829
11-30-2005 20:08:05.765 - Don't know to format (0x00000021, 0x000000ff) for tag 0x2a4d3263
11-30-2005 20:08:05.765 - Receive Carrier symbol rate: 8000
11-30-2005 20:08:05.765 - Receive Carrier frequency: 0
11-30-2005 20:08:05.765 - Initial transmit carrier data rate: 26400
11-30-2005 20:08:05.765 - Final transmit carrier rate: 26400
11-30-2005 20:08:05.765 - Initial receive carrier data rate: 50666
11-30-2005 20:08:05.765 - Final receive carrier rate: 45333
11-30-2005 20:08:05.765 - Carrier Rate re-negotiation event count: 0
11-30-2005 20:08:05.765 - Carrier Retrains requested: 0
11-30-2005 20:08:05.765 - Carrier Retrain requests granted: 0
11-30-2005 20:08:05.765 - Protocol Negotiation Result: V.42 LAPM
11-30-2005 20:08:05.765 - Error control frame size: 128
11-30-2005 20:08:05.765 - Error control link timeouts: 30
11-30-2005 20:08:05.765 - Error control link NAKs: 210
11-30-2005 20:08:05.765 - Don't know to format (0x00000044, 0x00000003) for tag 0x2a4d3263
11-30-2005 20:08:05.765 - Compression dictionary size: 2048
11-30-2005 20:08:05.765 - Transmit flow control: V.24 ckt 106/133
11-30-2005 20:08:05.765 - Receive flow control: V.24 ckt 106/133
11-30-2005 20:08:05.765 - Transmit characters sent from DTE: 509062
11-30-2005 20:08:05.765 - Transmit characters lost (data overrun errors from DTE): 0
11-30-2005 20:08:05.765 - Received characters sent to DTE: 2433301
11-30-2005 20:08:05.765 - Received characters lost (data overrun errors to DTE): 0
11-30-2005 20:08:05.765 - Transmit Frame count: 3819
11-30-2005 20:08:05.765 - Transmit Frame error count: 202
11-30-2005 20:08:05.765 - Received Frame count: 19067
11-30-2005 20:08:05.765 - Received Frame error count: 466
11-30-2005 20:08:05.765 - Call Waiting event count: 0
11-30-2005 20:08:05.765 - Termination Cause: CCT108 Turned Off
11-30-2005 20:08:05.765 - 115200,8,N,1, ctsfl=1, rtsctl=2
11-30-2005 20:08:05.765 - Initializing modem.
11-30-2005 20:08:05.781 - Send: AT<cr>
11-30-2005 20:08:05.781 - Recv: AT<cr>
11-30-2005 20:08:05.781 - Command Echo
11-30-2005 20:08:05.781 - Recv: <cr><lf>OK<cr><lf>
11-30-2005 20:08:05.781 - Interpreted response: OK
11-30-2005 20:08:05.796 - Send: AT &F E0 &C1 &D2 V1 S0=0\V1<cr>
11-30-2005 20:08:05.796 - Recv: AT &F E0 &C1 &D2 V1 S0=0\V1<cr>
11-30-2005 20:08:05.796 - Command Echo
11-30-2005 20:08:05.796 - Recv: <cr><lf>OK<cr><lf>

Many thanks for a great website and all the help,

The ati11 will give info about initial and final rates as well as retrains / rate renegs.
If you do a speed test and a retrain occurs during the test, the results will be very affected.
I have done various speedtests including the speakeasy one - they all have strengths/weaknesses - My favorite tool is still Net.Medic because of it's small size, and easy to read display giving a continuous display of throughput - see
www.modemsite.com/56k/x2-thru.asp

I just noticed that I never provided the ATI11 results that you requested.

This Airlink SV92PL based Modem performs better on the Internet based Speedtests if I limit the connect speed to 41333 or 42666 bps.

The results below were recorded with no speed limiting.

Any thoughts on what might be happening?

Description Status
--------------- ------------
Last Connection V.90
Initial Transmit Carrier Rate 24000
Initial Receive Carrier Rate 49333
Final Transmit Carrier Rate 26400
Final Receive Carrier Rate 42666
Protocol Negotiation Result LAPM
Data Compression Result V.42bis
Estimated Signal/Noise Ratio (dB) 47
Receive Signal Power Level (-dBm) 23
Transmit Signal Power Level (-dBm) 13
Round Trip Delay (msec) 15
Near Echo Level (-dBm) 18
Far Echo Level (-dBm) 73
Transmit Frame Count 4538
Transmit Frame Error Count 1
Receive Frame Count 12776
Receive Frame Error Count 662
Retrain by Local Modem 1
Retrain by Remote Modem 0
Rate Renegotiation by Local Modem 0
Rate Renegotiation by Remote Modem 2
Call Termination Cause 0
Robbed-Bit Signaling 0
Digital Loss (dB) 03
Remote Server ID NA

OK

By the way, I returned the Taicom International Hummingbird Modem using the Smartlink SL2800 chip.

I really didn't need any more modems, and it performed very poorly on two out of three initial connections. Limiting the speed could very well have helped but I didn't want to spend any more time on it. I also had the default WinXP driver and another driver supplied on CD.

I mentioned that it started working after cleaning the PCI edge contacts. I'm not positive that the contacts were in fact making a poor connection. The problem might have been my telephone line connection. I will never know for sure.

All of my other modems don't care which of the two telephone jacks are used. This modem, however, requires that you connect to the jack marked Line. Interesting that it works differently. I did notice that the jacks provided only two copper prongs for connection, while my other modems provide four.