Chapter 633 Your Trivia, My Treasure

When the two groups of people were ready to leave with their heads full of knowledge, Gao Zhendong only let the comrades from the Military Communications Institute go first, but kept the comrades from the Communications Institute.

The comrades from the Military Communications Institute did not take it seriously. They thought that everyone among these people had something they could not communicate with each other, so they left happily with the information.

The comrades from the Institute of Communications were even happier. This unplanned retention proved that it was probably a good thing.

Sure enough, Gao Zhendong made a phone call to the electronics laboratory of the third factory, and soon, comrades from the electronics laboratory came over with several small circuit boards and some information.

"Boss Gao, what is this?"

Gao Zhendong smiled and said, "I always feel that the dialing speed of the rotary phone is too slow, and there are some security issues. So I made you a dialing device."

The comrade from the Institute of Communications took the call and said, "Chief Engineer Gao, the current pulse dialing is a bit slow. We also want to solve this problem, but there is no good way."

Some say pulse dialing became obsolete because it required manual switching, but this is actually wrong.

For automation systems, automatically processing pulse signals is the simplest thing. Even decades after the widespread use of key dials, a considerable number of programmable switches still support automatic switching of pulse dialing for compatibility.

The main reason for phasing out pulse dialing is that it is slow, and another reason is that there are some security issues.

The pulse width of this thing is relatively wide. It's not so bad if the number you dial contains mostly 1s, but if there are more numbers above 5 including 0, it will be a torture, and the number dial will take a long time to run.

As for security, Gao Zhendong remembers that when he was a kid, he secretly called the family phone. Although the phone was locked in a box by his parents, the microphone was outside for easy answering. At this time, as long as he picked up the receiver and tapped the fork spring (the small square under the receiver) at a certain rhythm, 1 tap for 1, 0 taps for 10, and a little time between numbers, he could make a call.

As for why his push-button phone also supports pulse dialing, in fact, not only his, but almost all landline phones support it, for the sake of compatibility.

I am a little tired, but just tell me if you can fight.

However, security is not a problem for ordinary people. If a button breaks, they can still deal with it in an emergency. But the slowness is really hard to tolerate.

For the comrades in the Institute of Communications, it seemed possible to develop another type of dial-up circuit, but on the one hand, they felt that there was no demand for it and it was slow, so they just had to put up with it; on the other hand, they could not think of a low-cost way to transmit more than ten digits over the telephone line.

What Gao Zhendong made for them was the dual-tone multi-frequency (DTMF) dialing circuit invented by the Citigroup guys. Until now, this is still the dialing circuit for landline phones.

简单来说就是用4个高音和4个低音，两两搭配，所以叫双音（高、低）多频（8个频率），这种方式可以电话线上表征传输4*4=16个按键。

In fact, the DTMF dialing circuit can do other things, such as acting as a communication circuit to transmit numbers at a lower rate. The 16 digits can be regarded as 0 hexadecimal numbers from 16 to F, which can be barely used if properly encoded.

In fact, including mobile phones and landlines, after dialing a landline, you press the buttons here, and the landline will receive the DTMF signal of the buttons in real time. When calling a service number such as 400, you can press the number to select the service item after the call is connected. This is the same principle.

Remote control of home appliances by phone, which was popular for a while, also adopted this method to transmit control commands. It was very slow, but the circuit was simple, and this method did not require much speed anyway.

In Gao Zhendong's previous life, this thing basically appeared in the form of integrated circuit chips, and it was even possible that it was directly integrated into other chips. However, at this time, using the chip form would occupy the integrated circuit production capacity. Gao Zhendong simply used logic chips to make a small circuit board, which could be stuffed into the phone. Moreover, cheap phones could just use a dial, and it was not necessary to use this thing.

This thing is a high-end product in this era!

After listening to Gao Zhendong’s introduction, the comrades from the Communications Institute looked at this thing with shining eyes!
"This thing is good, this thing is good. Baby, baby!"

Gao Zhendong was totally confused. This was at best just a gadget to improve the user experience. What was so great about it?

"I can't really say baby, it's an optimization, hehe." Gao Zhendong really didn't know how to respond to this obviously too much flattery, so this was the only answer he could give for the time being.

When the comrades from the Communications Institute saw Gao Zhendong's reaction, they were stunned for a moment, then they thought about it, understood, and laughed.

"Chief Engineer Gao, I'm really not trying to flatter you. This thing may just be a small gadget for you..."

Hey, this is true. Gao Zhendong didn’t even spend a whole day on this thing. It’s just a little gadget.

"But for us, it's really a good thing! In our opinion, this thing is a simplified version of the modem you made, and it doesn't need to be used with a computer. It can do so many things!"

For the comrades at the Institute of Communications, with the existing telephone network's relay system, even if it is still manual switching, and even if the current telephone network cannot automatically identify the signal of this equipment, but within a certain distance, once the call is connected, this thing can serve as a telegraph machine.

All this can be done without expensive computers or modems, but with a simple circuit board and a 16-key keyboard. In his eyes, this is not a dial identification device attached to the telephone exchange system, but an independent communication device!
He even thought about making a telephone remote controller. Although there are not many home appliances that need to be controlled these days, this is a manifestation of superiority. Ordinary people can also use remote-controlled machines. This kind of publicity is much better than sending telegrams.

After hearing what he said, Gao Zhendong realized that although this thing in this era was simple, it did have some tricks.

Indeed, the available transmission rate of DTMF is pitifully low. According to regulations, a maximum of 10 keys can be pressed per second. Gao Zhendong also processed this in the circuit, which means that a maximum of 10 hexadecimal digits can be transmitted per second. Simple conversion means that the amount of data that can be transmitted per second is 16 bytes, which is 5bps in baud rate! Compared with the 40bps of Gao Zhendong's youth modem, it is extremely weak.

How weak is it? To give an intuitive example, for people who type fast, the transmission rate of this thing can hardly keep up with the speed of people typing on the keyboard.

However, no matter how slow it is, it really realizes the most basic data communication, the implementation method is relatively advanced, and the price is not expensive.

This thing, which was not valued at all in the communications field in the previous life, has now become a treasure, and a treasure with practical significance.

The 5-byte communication rate is fully usable for many data collection applications, even decades later. For example, the data collection in the water conservancy, environmental protection, meteorology and other industries that Gao Zhendong has been involved in can be transmitted every few minutes or tens of minutes, and the data transmitted each time is nothing more than a few dozen bytes.

It is indeed harmful to get too far ahead of others, as it will cause you to take many things lightly.

Thinking of this, Gao Zhendong laughed and said, "You know what, I really haven't thought about it in this direction. Anyway, this thing is here, how to use it is up to you guys to decide, hahahaha."

At this point, Gao Zhendong had to laugh it off to hide his embarrassment.

"Okay, Chief Engineer Gao, please rest assured, we will make good use of it." The comrades from the Communications Institute were very happy that they had succeeded this time.

The group said goodbye to Gao Zhendong and talked as they walked.

"Boss, Chief Engineer Gao doesn't seem to think highly of this thing."

"Of course. To him, this thing can only be used to send dial-up numbers. He has high standards."

"I think when you called this thing a 'treasure' just now, he must have thought you were trying to flatter him, hahahaha."

"That's nothing. I'd be happy to be flattered like this every day. Besides, Chief Engineer Gao's ability in this area is not flattery no matter how much you praise him."

"Well, let's go back and study it carefully. Before using this thing in program-controlled switching, let's use it in other places first. Even though the chief engineer doesn't like its high speed, it can be used for simple remote control that doesn't require high speed. It really works."

They became more and more excited as they talked.

"Why don't we just use this technology to make a dual-tone multi-frequency data transmission machine to transmit digital signals? 2.5 Chinese characters or 5 alphanumeric symbols per second is enough. Let comrades in other industries figure out how to use it."

"Hey, this is possible. We can also make a remote controller that can send 16 control commands or control 16 switches. It's also a good idea."

"Yes, yes, yes, we can do it, we can do it..."

"Come on, everyone, share your ideas and see what topics you can each work on."

"Yes, think of another one, think of another one. There are three of us here, one for each of us. Otherwise, if people from other courtyards next door see us, they will think we can't do it."

"Remember to put Chief Engineer Gao in the front. Don't forget the well-digger when you drink the water."

"Of course I'm not stupid. He has a high standard and we can't deny it."

"Why not make another one..."

"..."

They understood from Gao Zhendong just now that the transmission of this signal does not necessarily have to be over the telephone network. As long as the line quality meets the requirements, it can also run on ordinary lines.

So they start to try their best to show off their skills. If they have laid the foundation but still cannot come up with some applications, then they should give up as soon as possible.

(End of this chapter)