"FDMA and TDMA are not as complex as CDMA, and it is easy to divide the frequency into two segments that do not interfere with each other and time to cut, but the reception of the address code is too complicated."

"However, the need for military secrecy, only in this way can the probability of being monitored be reduced, and each user uses the same bandwidth, the same carrier, and can send and receive signals at the same time, using traditional filters and strobes can not separate the signals they want, which also realizes the needs of our secrecy work, right?"

Li Jian searched for the information related to the CDMA baseband chip in his mind, such as information, modulation, spread spectrum, carrier, and transmission.

Later generations of mobile phones are mainly divided into four main parts, radio frequency chips, baseband chips, power management and accessories, that is, keyboard display shells and other things, of which the baseband chip is the most important and the most high-tech, because there are CPU and other core chips in the cover.

The mobile phone adopts a streamlined architecture, which is very different from the complex instructions of Intar, but in the future, with the rise of mobile terminals, the complex instructions that occupy the main advantage in the early stage will be surpassed by the streamlined instructions.

The process of 1.5 microns should also be able to be realized in China.

Li Jian looked at Du Zihao,

"What level of craftsmanship are we at now? Three microns or five microns? ”

Seeing that Du Zihao's face was a little embarrassed, Li Jian knew that it must be five microns, and then he could enter the era of three microns, and then he would be one micron.

Don't look at just two small quantities, but the gap during the period is very different, which is equivalent to being led by foreign countries by two generations.

"It's up to you to solve it."

Li Jianben wanted to impulsively blurt out the words that he had joined the CDMA project team. But when I think about who I am, and what I have to do now. I really don't have the energy to engage in CDMA, and I have already given relevant information. Although it is not exhaustive to the specific operation, the principle is already there, and the people of the Science and Technology Commission and the military only need to realize the process from theory to practice.

The use effect of the base station is not bad to describe as unsatisfactory, which is not the same as walkie-talkies and cordless phones, but in the 900MHz frequency band using code division multiple access to achieve the call, the power of the base station is limited, but according to the current situation. This one base station can realize the coverage area of two ordinary GSM base stations, and within this coverage area, you can talk to other cauldrons by carrying this cauldron.

As long as the base station continues to be added, the distance of this call can continue to be extended, and theoretically the entire earth can be covered.

If Qianghua sets the next goal in the development of the IC industry, it should now acquire foreign wafer factories, and at present, there are 3.5-inch wafer factories in China, compared with foreign 5-inch factories, which has lagged behind a grade. But this kind of cost is not something that Li Jian can afford, let alone Qianghua, hundreds of millions of yuan, plus a large number of skilled workers. Qianghua does not have it at all now.

Therefore, Li Jian can only continue to focus on the communication industry with sufficient cash flow, but the communication business. It is just the first step on the road of Li Jian's development.

After leaving the 99th Army, Li Jian went to the Post and Telecommunications Bureau again. I went to see the first base station to be built with Qin Yuanzhi and several people from the technical department, the central base station located inside the Post and Telecommunications Bureau.

Field experiments. Qin Yuanzhi dialed the voice station with a silent phone, and the Daping brand pager produced by Qianghua entrusted by Qianghua to the county radio factory on his waist received the information prompt from Didi Didi a few seconds later, but because this was an analog signal, Qin Yuanzhi could only call the voice station again, and only then did he get the phone number to call himself, that is, the cordless phone number in his hand.

"Li Jian, you have a night view display on this pager, it won't be just to see the time, the analog signal can only be dialed back, it is a pure waste to use this LCD screen, it is better to only use a red light-emitting diode prompt, plus sound and vibration prompts, reduce the cost, and it is also convenient to apply in China."

Qin Yuanzhi was also happy to see the success of the experiment, but he asked Li Jianlai today to solve the problem, Daping pager is not bad compared with Motoraro's products, and even the LCD screen is much more beautiful than Motorolaro's gray products, but such flashy things, after all, can only be enjoyed by a few people in China, which can completely reduce costs and develop scale.

"Who says you can't show a phone number? There is an adjustment button here, dial to the left is the digital signal reception mode, and after your digital signal base station is built, you don't have to dial 126 manual station like now, you have to dial 127 electronic station directly, and the phone number can be sent. ”

Li Jian didn't have a special expression on his face when he said, but there was some faint unwillingness, if it weren't for the fact that the memory module of this era was too expensive, it was completely possible to add a small memory to the pager, such as 8K, 16K, such a small memory, used to store a voice, before the advent of mobile phones, it would definitely be able to sell well.

Memory is expensive, memory is expensive, can't you make a lot of money, but memory also needs integrated circuits and silicon wafer factories, the problem is back to the original point, Li Jian does not have this strength.

In my memory, there will be no memory manufacturers in China in the next few decades, and even if there are some memory brands, they have purchased memory chips from Hong Kong and Taiwan and returned to their factories to solder them by hand.

At present, there is already a 247 factory located in Xiwu in China, and they have just introduced the production line of large-scale integrated circuits from Zhidong Company like South Korea's Xingsan Company.

In this case, Qianghua does not need to contribute any manpower and material resources at all, just need to charge patent fees, but to collect patent fees, it is still necessary to choose a memory technology that does not currently exist.

It's just how to explain to people how you know about memory technology, I have exposed a lot of high-tech things, but from Chunjiang County to a little department, no one doubts, this is not scientific.

Li Jian didn't know that the Public Security Bureau and the State Security Bureau had already investigated his background and reported it to a certain level of upper echelons, and he felt strange that his skills had not attracted the attention of others. (To be continued......)