The Difference Between SYWV75-5 Line And SYV75-5

SYV-solid polyethylene insulation, also called "video cable".

SYWV-polyethylene physical foam insulation, also called radiofrequency cable or cable television cable.

Common points:

1. The characteristic impedance is 75 ohms;

2. The outer sheath, shielding layer structure, insulating layer outer diameter, number selection, material selection, shielding layer number, etc. are basically the same;

difference:

1. The physical properties of the insulating layer are different: SYV is filled with 99.999% polyethylene, and the dielectric constant ε=2.2-2.4; while SYWV is also filled with polyethylene, but it is filled with 80% nitrogen bubbles, and polyethylene contains only 20%. The average dielectric constant ε=1.4; ε=εˊ+jε", where ε" is the loss term, and the ε" of air is basically "0". This process was achieved in the 1990s, and it effectively reduces the coaxial cable’s Dielectric loss;

2. The diameter of the core wire is different: Taking 75-5 as an example, due to the specification of the -5 cable structure, the outer diameter of the insulation layer (ie, the inner diameter of the shielding layer) is 4.8mm, which cannot be changed. In order to ensure the characteristic impedance of 75Ω, the characteristic impedance is only related to the diameter ratio of the inner and outer conductors and the dielectric constant ε of the insulating layer. Large ε core wire is thin, ε small core wire is thick, core wire diameter: SYV is 0.78-0.8mm, SYWV is 1.0mm; the core wire structure can be used It is a single strand or multiple strands; this difference results in a difference in core wire resistance. According to the actual measurement of Tiancheng and Aipu SYV75-5 cable, the DC resistance of 1000m core wire is 39Ω, the typical SYWV75-5 cable, the DC resistance of 1000m core wire is 19-20Ω;

3. The above two fundamental differences determine the transmission characteristics of the two the transmission attenuation is different. SYV cable is the earliest coaxial cable. It has been used for tens of hundreds of years for transmission, including transmission of radio frequency signals; but later when SYWV appeared, SYV was rarely used in the band above radio frequency. Because the difference in high-frequency attenuation is too large; slowly, SYV is basically mainly used for surveillance video transmission, so the "old man" of this kind of radio frequency cable is renamed "video cable". But this is not the same as saying: that SYV "video cable" has better video transmission characteristics than SYWV. In fact, it is just the opposite. SYWV's video transmission characteristics are also better than SYV cable. Misunderstandings in this area are very common, and the misunderstandings in southern China are more serious than those in the northern country. They believe that to transmit video signals, "video cables must be used." Measured video transmission performance of 1000 meters cable, SYWV75-5/64 series cable: 0.5M—5.15db, 6M—19.12db; national standard high quality SYV75-5/96 series cable: 0.5M—6.43db, 6M—21.76db (same series The attenuation of the net structure cable is 3db larger than that of the foamed cable-that is, more than 1.4 times), there is a quite famous manufacturer's product, the SYV75-5/128 braided cable, 6M-25.22db, the attenuation is more than 6db larger than that of the foamed cable— -That is more than 2 times larger);

4. Regarding high braided cables, generally refer to cables above 96-128 braid. The obvious characteristics of high-stranded cables are: that the shielding layer has a small DC resistance, and the low-frequency attenuation below 200KHz is reduced, which is beneficial to suppressing low-frequency interference. The actual measurement shows that at 200KHz-6MHz frequency, due to the "skin effect", 128-strand and 64-strand attenuation are the same. (The high-frequency current only flows on the outer surface of the core wire and the inner surface of the shielding layer). From the perspective of frequency distortion (high and low-frequency attenuation difference), high-braided cables are on the contrary serious. The direct influence of frequency distortion is the normal proportional distortion of the various frequency components of the video signal, which directly affects the image distortion;

5. Copper-clad steel core wire: This is a kind of SYWV cable, used for the radio frequency transmission of CATV above 46MHz. Due to the "skin effect", the current only flows in the copper skin outside the steel wire, with attenuation characteristics and pure copper core The cable is the same, but the tensile strength is much higher than that of copper wire; but this kind of cable is not suitable for video transmission, and the low-frequency attenuation of 0-200KHz is too large;

Whether to use SYV or SYWV is more dependent on the user's experience and habits. Both have their own advantages, and there are high-quality or inferior products.

Hangzhou Putianle Cable Co., Ltd. independently developed braiding machine take-up equipment to ensure the stability of the tension of the braided outer conductor of the coaxial cable, thereby ensuring the stability of product performance. It has one 90-type physical foaming production equipment and three 65-type physical foaming production equipment production lines of Shanghai’s 23 Cable Research Institutes, 135 high-speed braiding machines with 16-ingot production lines, more than 10 24-ingot production lines, and 5 sheathing production lines. 6 Metronics computer inkjet printers, equipped with corresponding testing equipment, the existing production capacity is more than 300,000 kilometers, and the annual output value can reach more than 100 million yuan.

① In terms of electrical performance testing, the company is equipped with the American Agilent network analyzer test system and PIM third-order intermodulation test system, which can comprehensively test the electrical properties of the cable, such as standing wave, attenuation, and impedance, to ensure that every meter of the cable is delivered. All fully meet the requirements of customers.

② With the rapid development of mobile communication technology, customers in this field require their products to have higher quality and reliability than the original. The current CDMA800, GSM900, DCS1800, 4G wireless communication networks, and the higher-performance fifth-generation wireless communication network (5G) place extremely high requirements on the performance of various passive components, such as cables and connectors.