The old system worked because it was profitable for utility companies to invest in the infrastructure. It became part of the rate base that determined the level of the "reasonable return on investment" they were entitled to by law.
NO it does not do ANY damage to your pc to turn it off,
Sorry, you're wrong about that. Every time you turn the power off and on you subject the circuitry to surge currents and thermal cycling.
This increases the failure rate of components and connections. With properly designed equipment, it isn't much of a problem. With aging or poorly designed equipment, there is a noticable increase in equipment failure rates.
The lack of new power generating facilities is also a factor. Ideally, power generation would be geographically close to its load. Due to NIMBY, it doesn't get built or it gets built "somewhere else", exporting the pollution and problems to someone else's backyard. This has led to increasing amounts of power being transported across the grid, from regions with surplus capacity to regions with permanent deficits in power generation.
Synchronous has nothing to do with speed. It refers to how bit timing is handled on the communications link. There is nothing to prevent a synchronous communications link from using different clock rates on the transmit and receive sides of the link.
The RF modem in the cable box is very similar to the RF modem in the "cable modem" that you buy to get broadband Internet via cable. The RF modem in the cable box is just dedicated to providing a data link between the computer in the cable box and the cable operator's servers.
In any business, especially a retail store, the per-item overhead can dwarf the wholesale/bulk price of an item. You are paying for ordering, inventory, floor space and other costs. With a vendor like Cisco or Sun, they have to specify, test and qualify the item, assign it a part number, stock it in warehouses, provide packaging and documentation, etc.
If it's a Courier, you're paying for the firmware, performance and the features of the modem. The market for these modems is relatively price-insensitive. It is much more important that they work reliably. I've used them for commercial applications where a few minutes of down-time would wipe out any cost savings gained by buying cheaper modems. In my situation, some people at the other end of the link tried to save money by buying Sportster modems. They ended up ripping them out and replacing them with Couriers after everyone wasted huge amounts of time and money on trying to make the communications links (international dial-up) work reliably.
Several large cable companies have said that they want to move everyone from analog to digital cable. This will allow them to shutdown all of the analog channels, providing a major boost in capacity to their systems. What they are waiting for is a digital cable convertor box that is cheap enough to distribute to all of their analog customers in a free upgrade to digital cable.
Existing digital cable boxes already have a built-in RF modem to support the program guide and pay-per-view ordering. It probably wouldn't cost much to add an external Ethernet interface for connecting to the user's computer.
Mail service should be decoupled from Internet access service. There are a number of valid reasons why a customer may not want to use his ISP's mail server, such as security, reliability and performance. Many ISPs have shown that they are incompetent in running their own mail servers.
Tell me about the morality inherent in using a greatly superior negotiating position to dictate unfair terms to the other party.
Even if you already have a job, some executive can get a bright idea and the next thing you know, some HR droid is giving you an agreement to sign. You don't have to sign it, just pack your things and turn in your badge if you don't like it.
The problem is that AMPS is used by a dwindling number of users and there isn't enough spectrum at 800 MHz to keep it and 800 MHz CDMA/GSM/TDMA running at full capacity. AMPS will eventually disappear, at least in urban areas where channel capacity is a problem. The FCC is planning to remove the requirement to support AMPS within 5 years.
There is an interesting story in the Atlanta Business Chronicle about Cingular getting hit with a $12M fine in California for the poor way that they ran their network and treated their customers.
UDP is ideal for latency sensitive data, like real-time telemetry. It does require that you have excess bandwidth or control over who has access to the network if you want to avoid dropped packets.
The NICs are cheap and the prices of the switches are dropping. I don't think it will be that long before gigabit Ethernet starts to push 100 Mbit Ethernet out of the market.
Vanilla Ethernet can be extremely reliable, without any additional layered protocols. I would be much more concerned about the reliability of the installation's AC power supply and distribution system.
I like the idea. Ethernet hardware is dirt cheap and fast. What it needs is a cheap IDE bridge board. That would let you put some IDE drives in an external enclosure and plug them into the local LAN.
Part of the problem is the damage caused to NASA by years of budget cuts. I saw this first hand. Due to a lack of funds, NASA adopted an attitude that sustaining engineering and operations costs could be substantially reduced by avoiding change whenever possible. Just keep the current system running with as little maintenance as possible. If nothing changes, you can get rid of most of the people who used to design, test, document and maintain the systems. If there is a problem with a system, you don't find the root cause and fix it, you develop a work-around. If new technology offers a better way to do something, you ignore it because the old system is "good enough" and you no longer have the money, infrastructure and people needed for major design changes and new systems development. The organization gets reduced to a caretaker for the engineering accomplishments of previous generations. It has just enough money and people to maintain the status quo.
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The old system worked because it was profitable for utility companies to invest in the infrastructure. It became part of the rate base that determined the level of the "reasonable return on investment" they were entitled to by law.
Sorry, you're wrong about that. Every time you turn the power off and on you subject the circuitry to surge currents and thermal cycling. This increases the failure rate of components and connections. With properly designed equipment, it isn't much of a problem. With aging or poorly designed equipment, there is a noticable increase in equipment failure rates.
The lack of new power generating facilities is also a factor. Ideally, power generation would be geographically close to its load. Due to NIMBY, it doesn't get built or it gets built "somewhere else", exporting the pollution and problems to someone else's backyard. This has led to increasing amounts of power being transported across the grid, from regions with surplus capacity to regions with permanent deficits in power generation.
VBR = Variable Bit Rate
CBR usually means that the bandwidth is reserved. You are guaranteed the specified data rate. Telephone calls normally use 64 kbps CBR circuits.
MTTR = Mean Time To Repair
The average time it takes to return a broken device or circuit back to service after it fails.
See ANSI T1.413-1998.
Synchronous has nothing to do with speed. It refers to how bit timing is handled on the communications link. There is nothing to prevent a synchronous communications link from using different clock rates on the transmit and receive sides of the link.
The RF modem in the cable box is very similar to the RF modem in the "cable modem" that you buy to get broadband Internet via cable. The RF modem in the cable box is just dedicated to providing a data link between the computer in the cable box and the cable operator's servers.
In any business, especially a retail store, the per-item overhead can dwarf the wholesale/bulk price of an item. You are paying for ordering, inventory, floor space and other costs. With a vendor like Cisco or Sun, they have to specify, test and qualify the item, assign it a part number, stock it in warehouses, provide packaging and documentation, etc.
If it's a Courier, you're paying for the firmware, performance and the features of the modem. The market for these modems is relatively price-insensitive. It is much more important that they work reliably. I've used them for commercial applications where a few minutes of down-time would wipe out any cost savings gained by buying cheaper modems. In my situation, some people at the other end of the link tried to save money by buying Sportster modems. They ended up ripping them out and replacing them with Couriers after everyone wasted huge amounts of time and money on trying to make the communications links (international dial-up) work reliably.
Existing digital cable boxes already have a built-in RF modem to support the program guide and pay-per-view ordering. It probably wouldn't cost much to add an external Ethernet interface for connecting to the user's computer.
What's the velocity factor of chocolate?
Mail service should be decoupled from Internet access service. There are a number of valid reasons why a customer may not want to use his ISP's mail server, such as security, reliability and performance. Many ISPs have shown that they are incompetent in running their own mail servers.
Even if you already have a job, some executive can get a bright idea and the next thing you know, some HR droid is giving you an agreement to sign. You don't have to sign it, just pack your things and turn in your badge if you don't like it.
The problem is that AMPS is used by a dwindling number of users and there isn't enough spectrum at 800 MHz to keep it and 800 MHz CDMA/GSM/TDMA running at full capacity. AMPS will eventually disappear, at least in urban areas where channel capacity is a problem. The FCC is planning to remove the requirement to support AMPS within 5 years.
There is an interesting story in the Atlanta Business Chronicle about Cingular getting hit with a $12M fine in California for the poor way that they ran their network and treated their customers.
Can you use coherent detection if all you have is the output of the demod?
UDP is ideal for latency sensitive data, like real-time telemetry. It does require that you have excess bandwidth or control over who has access to the network if you want to avoid dropped packets.
The NICs are cheap and the prices of the switches are dropping. I don't think it will be that long before gigabit Ethernet starts to push 100 Mbit Ethernet out of the market.
My experience is that a properly installed and tested Ethernet network is very reliable.
Vanilla Ethernet can be extremely reliable, without any additional layered protocols. I would be much more concerned about the reliability of the installation's AC power supply and distribution system.
I like the idea. Ethernet hardware is dirt cheap and fast. What it needs is a cheap IDE bridge board. That would let you put some IDE drives in an external enclosure and plug them into the local LAN.
The Borg may have drones and state-of-the-art technology, but we have lawyers, millions of lawyers.
Part of the problem is the damage caused to NASA by years of budget cuts. I saw this first hand. Due to a lack of funds, NASA adopted an attitude that sustaining engineering and operations costs could be substantially reduced by avoiding change whenever possible. Just keep the current system running with as little maintenance as possible. If nothing changes, you can get rid of most of the people who used to design, test, document and maintain the systems. If there is a problem with a system, you don't find the root cause and fix it, you develop a work-around. If new technology offers a better way to do something, you ignore it because the old system is "good enough" and you no longer have the money, infrastructure and people needed for major design changes and new systems development. The organization gets reduced to a caretaker for the engineering accomplishments of previous generations. It has just enough money and people to maintain the status quo.
When you live in the sewer, it's considered rude to complain about the other rats.
That lack of interest can disappear very quickly if your part-time project becomes a commercial success. Greed is a great motivator.