also, every critical system is on a closed network so our infrastructure will not fall apart.
You wish.
Closed networks on leased lines are damn expensive. It is much cheaper to connect systems over the Internet, and pray that the firewall and/or VPN will keep out the bad guys.
Because they are afraid that we are going to wake up some morning, and find a large number of computers that have been effectively destroyed, causing massive damage to the economy and the country. There may not be any corpses, but that won't make the aftermath any better.
If you are talking about a secure version of UNIX or Windows, sure, it would be very difficult. It's like trying to modify an automobile into an airplane. It can be done, but the result is going to suck.
Security has to be designed in from day one, not retrofitted on to an insecure system.
What's needed is the financial and legal motivation to design, build and deploy secure systems.
One of the principles of satellite design is KISS (Keep It Simple Stupid). Complicated designs kill your reliability and increase costs. Another principle is that if you have the choice between doing it on the satellite and doing it on the ground, you do it on the ground. You can always repair and upgrade ground-based equipment.
There are several advantages to the simple transponder. One, is the low component count, improving reliability. Two, it supports multiple types of services, even services that had not been invented when the satellite was designed. A single transponder can simultaneously support multiple sources of voice, data and video, whether digital or analog.
To be jam resistant, a spread spectrum transponder is going to need a very large and linear dynamic range, plus a very wide bandwidth. Otherwise, a single strong carrier will be able to suppress any weak signals.
The problem is that transponders are relatively simple devices. They receive a band of frequencies and retransmit those frequencies on another band. Anything in the uplink passband is duplicated in the downlink passband. The transponder can be jammed simply by putting a very strong unmodulated carrier in the uplink passband. This hogs all of the power available in the downlink section of the transponder, leaving little or no power for the legitimate users.
A sophisticated antenna system will provide steerable nulls in its radiation pattern. Once the source of the interference is localized, the antenna can be adjusted to place the null over the source of interference.
What if the bar is owned by the VP's brother-in-law? The VP organizes periodic trips of "volunteers" to go to the bar and spend large sums of money, which are reimbursed by the corporation as meal expenses. It's a neat way of sucking money out of the corporation. Better yet, have the corporation charge the expenses against some recording artist's contract. Hey, it was a business meeting to discuss who should be in the artist's next music video.
The big deal is that in the old days, the police or FBI had to present a court order to the telephone company to get a wiretap. A telephone company technician installed the wiretap, not an FBI agent. With the new systems, they have removed the telephone company's participation, making it a self-serve system. What is the software going to do, put up a dialog box saying "Do you have a lawful court order? [Y/N]"? This is bad news in a society where many police officers believe that the end justifies the means.
The problem is that the diesel sub has to recharge its batteries on a regular basis. With modern sonar surveillance networks, running a diesel engine on the surface is like putting up a flashing neon sign saying "sub here, sink me!".
900 MHz is an ISM (Industrial, Scientific, Medical) band, like the 2.4 GHz band. Unlicensed devices may not cause interference to licensed users and they must accept interference from other devices. This means that you are at the bottom of the totem pole in a "junk" band. If you can't use your unlicensed 900 MHz device due to interference, tough shit, that's the price you pay for unlicensed operation in an ISM band. Devices designed for ISM bands are usually designed with low cost as the primary design goal. That often means that there is no shielding and the RF electronics function poorly, or not at all, in a hostile RF environment.
The end result is that you should keep your expectations low. If it works, great, if not, try something else.
I would check with your state's public utility commission before making any decisions. Going into the telephone business may require more than just hooking up some hardware.
It takes time, money and engineering to build a reliable network. Back in the days of the Bell System, a great deal of effort was expended in improving the reliability of the hardware and the network. There were redundant paths, load balancing and excess capacity built into the network. Huge amounts of money were spent on making electronic switching systems, and the associated software, extremely reliable.
The Bell monopoly is gone. So are the economic conditions that made it possible to spend all that money on reliability. Today, the emphasis is on fast, cheap and disposable. Telephones are no longer designed to last decades. Single points of failure are acceptable if they result in consolidation and costs savings. Experienced workers have been downsized and replaced with cheap contractors.
Many of the people who design IP networks have no interest in reliability beyond "it works most of the time". Single points of failure abound in their networks, which are usually built from mediocre hardware running software that is in perpetual beta test.
Look at the popularity of VOIP and PC based switches. People are eager, even if they don't think about it, to trade reliability for cash. Why spend big bucks on a purpose-built PBX when we can do it on a PC running Windows with some add-ons? Why spend money on backup power, redundancy and failure tolerance?
Reliability costs money and there are damn few people who are willing to pay the price. That is reflected in the marketplace for hardware, software and communications services.
A portion of the transmit audio is also mixed in to the receive audio. If you don't do this, people think the phone is broken. Analog phones do this by unbalancing the hybrid that separates transmit and receive audio.
How hard would it be to do this the old-fashioned way, on paper, with filing cabinets? The federal government could build a records repository and have the schools mail in the forms.
And who picks the voting machines in Florida and in most states? The county governments. So are "black" counties conspiring to suppress the votes of their citizens?
Military pilots run into similar problems at much lower speeds. It is very easy to kill yourself and destroy the aircraft while flying at hypersonic speed. Just yaw the aircraft a bit and the airflow will rip it to shreds.
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You wish.
Closed networks on leased lines are damn expensive. It is much cheaper to connect systems over the Internet, and pray that the firewall and/or VPN will keep out the bad guys.
Because they are afraid that we are going to wake up some morning, and find a large number of computers that have been effectively destroyed, causing massive damage to the economy and the country. There may not be any corpses, but that won't make the aftermath any better.
Security has to be designed in from day one, not retrofitted on to an insecure system.
What's needed is the financial and legal motivation to design, build and deploy secure systems.
Fatal error: Call to undefined function: message_die() in db/db.php on line 88
What do you do when the GPS unit breaks or the batteries crap out? Become buzzard food?
There are several advantages to the simple transponder. One, is the low component count, improving reliability. Two, it supports multiple types of services, even services that had not been invented when the satellite was designed. A single transponder can simultaneously support multiple sources of voice, data and video, whether digital or analog.
To be jam resistant, a spread spectrum transponder is going to need a very large and linear dynamic range, plus a very wide bandwidth. Otherwise, a single strong carrier will be able to suppress any weak signals.
A sophisticated antenna system will provide steerable nulls in its radiation pattern. Once the source of the interference is localized, the antenna can be adjusted to place the null over the source of interference.
Disneyland Memorial Orgy by Wally Wood.
What if the bar is owned by the VP's brother-in-law? The VP organizes periodic trips of "volunteers" to go to the bar and spend large sums of money, which are reimbursed by the corporation as meal expenses. It's a neat way of sucking money out of the corporation. Better yet, have the corporation charge the expenses against some recording artist's contract. Hey, it was a business meeting to discuss who should be in the artist's next music video.
They bugged every room in the Intourist hotel in Moscow. Some rooms had still, motion picture or video cameras.
The big deal is that in the old days, the police or FBI had to present a court order to the telephone company to get a wiretap. A telephone company technician installed the wiretap, not an FBI agent. With the new systems, they have removed the telephone company's participation, making it a self-serve system. What is the software going to do, put up a dialog box saying "Do you have a lawful court order? [Y/N]"? This is bad news in a society where many police officers believe that the end justifies the means.
The problem is that the diesel sub has to recharge its batteries on a regular basis. With modern sonar surveillance networks, running a diesel engine on the surface is like putting up a flashing neon sign saying "sub here, sink me!".
The end result is that you should keep your expectations low. If it works, great, if not, try something else.
That would be 9-track 1/2" tapes, the kind used on "real computers". It isn't a real computer if it doesn't have a motor-generator and water cooling.
I would check with your state's public utility commission before making any decisions. Going into the telephone business may require more than just hooking up some hardware.
I don't know if it is a problem in Hungary, but some countries get blacklisted due to credit card fraud.
U.S. law enforcement agencies and the TLAs do not want cellular users to have ubiquitous encryption.
Warrants? Warrants? We don't need no stinking warrants!
There are languages designed for business applications, like COBOL.
It takes time, money and engineering to build a reliable network. Back in the days of the Bell System, a great deal of effort was expended in improving the reliability of the hardware and the network. There were redundant paths, load balancing and excess capacity built into the network. Huge amounts of money were spent on making electronic switching systems, and the associated software, extremely reliable.
The Bell monopoly is gone. So are the economic conditions that made it possible to spend all that money on reliability. Today, the emphasis is on fast, cheap and disposable. Telephones are no longer designed to last decades. Single points of failure are acceptable if they result in consolidation and costs savings. Experienced workers have been downsized and replaced with cheap contractors.
Many of the people who design IP networks have no interest in reliability beyond "it works most of the time". Single points of failure abound in their networks, which are usually built from mediocre hardware running software that is in perpetual beta test.
Look at the popularity of VOIP and PC based switches. People are eager, even if they don't think about it, to trade reliability for cash. Why spend big bucks on a purpose-built PBX when we can do it on a PC running Windows with some add-ons? Why spend money on backup power, redundancy and failure tolerance?
Reliability costs money and there are damn few people who are willing to pay the price. That is reflected in the marketplace for hardware, software and communications services.
Save the planet. Recycle an environmentalist.
A portion of the transmit audio is also mixed in to the receive audio. If you don't do this, people think the phone is broken. Analog phones do this by unbalancing the hybrid that separates transmit and receive audio.
How hard would it be to do this the old-fashioned way, on paper, with filing cabinets? The federal government could build a records repository and have the schools mail in the forms.
And who picks the voting machines in Florida and in most states? The county governments. So are "black" counties conspiring to suppress the votes of their citizens?
Sorry, the City of Chicago has been granted a "business process" patent on fixing elections.
Military pilots run into similar problems at much lower speeds. It is very easy to kill yourself and destroy the aircraft while flying at hypersonic speed. Just yaw the aircraft a bit and the airflow will rip it to shreds.