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What is a 56K modem

A modem which implements one of the 56K protocols (V.90, X2 or K56Flex). 56K modems rely upon digital service at the remote end of the connection to achieve a 56K rate (i.e. a rate above 33.6Kbps, 33.6 kilo-bits per second). The 56K transfer is asymmetric, with the download side reaching a maximum speed of 53K (FCC limits restrict the '56K' rate to a maximum best of 53K), and the upload side, 33.6K.

What is V.90

V.90 is the standard, established by the International Telecommunications Union (the ITU), for 56K modem communications (i.e. modem rates above 33.6K). The ITU is a world-wide body responsible for modem communication standards. The V.90 standard was developed to ensure a uniform manner by which modems can communicate between one another at the fastest possible rate over plain old telephone service (POTS) equipment.

About X2 and K56Flex

Both X2 and K56Flex are proprietary 56K protocols. X2 was released by 3Com/ U.S. Robotics and K56Flex by a coalition of modem manufacturers using the Rockwell/Conexant and Lucent chipsets. Both protocols have now been superceded by V.90 as the official 56K standard. If your modem runs X2 or K56Flex, it is strongly recommended that you upgrade it. Although some older X2 and K56Flex modems could not be upgraded, for most upgrading can be done through installing new software (firmware and driver) for the modem. This software is generally provided by the pc or modem manufacturer and made available on their website.

Does V.90 make X2 and K56Flex work together

No. V.90 is a 56K protocol standard separate from both X2 and K56Flex. It does not allow X2 to work with K56Flex. Both modems on each side of the connection must be upgraded to V.90 before they can communicate at 56K rates. However, a V.90 modem which has been upgraded from X2 can, barring any inter-operability issues, communicate at 56K rates with a V.90 modem which has been upgraded from K56Flex.

What 56K protocols does Green Apple support

Green Apple supports V.90 primarily. We also support X2, but would urge X2 users to upgrade their modem to the V.90 standard. K56Flex modems which want to connect to Green Apple at 56K speeds (speeds above 33.6Kbps) need to be upgraded to V.90.

How do I upgrade my 56K modem to V.90

That will depend upon your pc or modem manufacturer. Most manufactures have committed to providing free or low cost upgrades. Upgrading a modem to V.90 involves installing a new firmware, installing a new driver or both. The only way to find out for sure is to check with your pc or modem manufacturer. Manufacturers who have upgrades available generally have them posted on their websites. For information on upgrading modem software, links to many manufacturers websites and additional information, please see: www.greenapple.com/support/library/ModemDB.htm

As an aside, manufacturers are continually making improvements to their V.90 software; even if your modem is currently V.90, it is a good idea to check with the manufacturer's website every couple of months to see if they have released a new firmware or driver for it.

I have a V.90 modem, but I connect around 46K-52K

Even though the family of modem standards which includes V.90, X2 and K56Flex has been named '56K', that labeling is misleading. For reasons having to do with the level of cross-talk experienced at phone companies central offices (the telephone switching centers), the FCC has limited the maximum speed of these protocols to 53K. Moreover, all the 56K standards, including V.90, are highly dependent upon the circuit from the originating point, such as your home, to the teleco's central office.

I have a V.90 modem, but I cannot connect above 33.6

To achieve 56K rates, you must have a clean phone connection. 3Com/U.S. Robotics has provided an easy to use line testing facility that people may use to evaluate the signal quality of their phone line and determine whether it is capable of 56K speeds. For information on using this, please see: http://modemupdate.usr.com/56k/need4_56k/linetest.html

Information on Area Central Offices

One requirement of 56K service is the switch quality in the central office of the phone company. Below is a synopsis of our experience using 56K with the three telephone providers in the area.

Ameritech: Much of the Ameritech serviced connections in Green Apple's service area will deliver 56K speeds (speeds higher than 33.6K). But this is not universally true: at least one Ameritech central office (the Rushville one), does not support 56K rates.

Verizon (GTE): The majority of Verizon serviced customers will not connect above 33.6K. Sorry to say, but GTE has not installed the necessary equipment in their Central Offices to allow for 56K. Some people who are very close to a GTE CO may get higher speeds, but they are the exceptions only.

United: For those of you in a United serviced area, the situation is even worse than in Verizon serviced areas. A best connection will be near 28.8K. Again, due to facility unsuitability.

A last comment. Issues such as the distance from your home to the central office which serves you play a role. Although we see very good connection rates throughout the Ameritech regions, we have seen signal quality issues in outlying Ameritech areas making 56K rates un-achievable.

If I am connecting from an area with poor connections, should I bother with a 56K modem

There is universal agreement among experts that 56K modems are better modems. As such, even though you may not get a 56K connection you will probably see higher throughput than you did with a non-56K modem. The exception to 56K modems being better than 33.6K modems are the Host Signal Processing, HSP, modems (aka. Software modems). For more information, please see: www.greenapple.com/support/library/ModemDB.htm

I have a 56K modem running V.90, and, although it reports that I have a faster connection, my computer seems to run slower

Most likely you have purchased a Host Signal Processing, HSP, modem. The most common of these uses the PC-Tel chip. These modems do not have a true 'data pump', but rather use the main central processing unit, the cpu, of your computer to do the signal processing.

While this seems a very cost effective way to deliver modem functionality, it does so at the expense of overall system performance. The fact is that a 33.6K standard modem often out-performs a 56K Software Modem in systems where all other components, such as processor type and speed, are equal.

Our Experience With Different 56K Modem Types

There are three types of 56K modems: Hardware modems, Winmodems and Host Signal Processing, HSP, modems. Hardware modems can be either external or internal and include all traditional modem components, a line codec, data pump, controller and bus interface. Winmodems are internal modems and substitute a virtual device driver for the controller (and include a COM port emulator). HSP modems have only a line codec and bus interface, with the other two components off-loaded to the CPU.

External Hardware modems. Good modems. If you have an available and working external COM port and don't mind spending a little more, these are probably the best bet. USR Courier and Sportster are very good. Have had less problem with these modems than any other. They are, however, the most expensive modem type.

Internal Hardware (ISA) Modems. The only modem in this class we have experience with is the USR Sportster (not referring to Sportster Winmodem here). This is a very good modem. Very low level of problems. A little less expensive than an external Sportster. Of course, you need to open the case to install it. Although the Sportster internal is plug-n-play, you often need to manually set the jumpers to get it to work (esp. with older motherboards). Many other models of hardware modems do connect near 56k speeds, but often require the latest driver in order to function properly. Older machines tend to have better luck getting these to work and get high speeds.

Winmodems. It is claimed that Winmodems are worse than Hardware modems because they off-load the controller and COM port functions to the cpu. On the other hand, it is also claimed that load incurred by off-loading is no more expensive for the cpu than the load incurred in handling communication over a COM port. We have had very good results with some Winmodems, although in the period of migrating from K56Flex to V.90, there seemed to be endless problems with drivers and firmware. The problems have been ironed out over time. LT Winmodems, with latest firmware and driver, perform very well and are the standout Winmodem. LT Winmodem is followed closely by the USR Sportster Winmodem. Rockwell/Conexant HCF chipset modems have come a long way since their introduction, but are still not quite up to the Lucent or USR. Winmodems have fewer component than a Hardware modem and, so, are less expansive. One consideration when purchasing a Winmodem (and this is doubly true for an HSP modem) is the extra complexity of a virtual device driver operating in a not always stable Win95/98 operating system.

HSP modems. The least expensive type of modem. They consists of a line codec and bus interface only. HSP modems have been the most troublesome 56K modem we have seen in terms of functionality and driver availability. HSP modems are notorious for affecting system performance as the modem data pump, controller and COM port are off-loaded to the cpu. Moreover, HSP modems chew up many clock cycles in managing the data flow over the PCI bus. Generally a P233-MMX is a minimum recommendation to run an HSP modem. Often though, once the latest driver is installed, the modems function reasonably.

For more information on different modem types, please see: www.greenapple.com/support/library/ModemDB.htm

Will two V.90 modems communicate at a rate higher than 33.6K when dialed directly to one another

This is a scenario seen when your modem connects to a typical BBS or to a friends machine to play games. For most situations, the answer is no.

Like the other 56K protocols, V.90 only delivers the higher speed when connecting to a digital provider. The vast majority of homes do not have digital service. This is normally found only with High Capacity (HICAP) providers such as Green Apple. If you connect directly to a friends computer the best connection you can ordinarily expect is 33.6Kbps.

This aspect of 56K is particularly confusing to many folks. Basically, the higher speed is only delivered on the receive channel of the modem. The 56K standards rely on specific characteristics of digital connections which do not exist with analog circuits. Expecting that most people only care about the speed they receive information, with less concern for how quickly they send it, V.90 takes advantage of these digital characteristics to maximize the receive end while maintaining the older protocol (i.e. V.34 with a maximum speed of 33.6Kbps) for the transmit side.

Related Green Apple Resources

For information on troubleshooting a connection problem, please see
    www.greenapple.com/support/library/ConnectivityDiag.htm

For more information and resources on modems, please see
    www.greenapple.com/support/library/ModemDB.htm

For information on configuring an Internet connection for your operating system, please see
    www.greenapple.com/support/library
 

 
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