Still nothing to post: October 2017

Friday, October 20, 2017

Comparison of cheap RF modules with ASK modulation. Part 4. Conclusions.

Disclaimer. Anything in this article is a private opinion guaranteed by Universal Declaration of Human Rights (UDHR). The author doesn’t impose it to anybody. Parameters are shown in this article are relative, and don’t reflect standard parameters of this type of the devices. If one would use different methods of measuring (or different types of measuring devices), the result different. The author doesn’t bear any responsibility for any consequences related to devices described in this article, including a lost profit. Decisions made by a reader are implemented at his own risk. Manufactures who think they are defamed can present their own refutations and the author will publish them with (or without) changing his own opinion.

  The 1st part with methods described.

  The 2nd part with transmitters results.

  The 3rd part with receivers results.

Part 4. Conclusions

The best way to get a good RX/TX device is to buy more expensive and complicated device or DIY.

But everybody wants to buy cheap modules and get good parameters. It can be acquired, but one should check these devices by himself. Many modules I ordered as a 315MHz came as a 433MHz. Many modules were unstable or even broken.

From modules below I cannot point to the best module and recommend it to somebody. Each module has its own disadvantages.

Summary table for transmitters modules:

Number, photo and sizes (in mm)	Current consumption in transmission mode	F1, MHz L, dB (More is better)	F2, MHz L, dB (less is better)	F3, MHz L, dB (less is better)
TX315-1 19x18x7 (w/o pins)	10mA	315,231MHz -66dB	628,86MHz -70dB	945,182MHz -78dB
	Comments: Unstable module.
TX315-2 11,5x11,5x6	10mA	315,068MHz -68dB	N/A	N/A
	Comments: Good, but not powerful module.
TX315-3 10x10x3	Sp.ant.: 7mA Pin ant.: 8mA	Spiral antenna: 315,05Mhz -72dB Pin antenna: 315,05Mhz -70dB	Spiral antenna: 630,0Mhz -97dB Pin antenna: 630,0Mhz -96dB	N/A
	Comments: Good, but not powerful module.
TX433-1 12,5x17x4 (w/o pins)	47mA	Main band: 433,79MHz -44dB 2 parasitic side bands: 447,35 and 420,23MHz -88dB	867,79MHz -83,5dB	1301,64MHz -74,0dB
	Comments: Maybe it has the bad matching with the antenna.
TX433-2 19x18x7 (w/o pins)	47mA	433,180MHz -55dB	867,444MHz -67,5dB	1301,708MHz -57,5dB(!)
	Comments: Unstable module.
TX433-3 11,5x15x6	16mA	433,939MHz -66dB	N/A	N/A
	Comments: Good, but not powerful module.
TX433-4 11,5x15x7	88mA	Spiral antenna: 433,95Mhz -56dB Pin antenna: 433,9Mhz -51dB	Spiral antenna: 867,84Mhz -95dB Pin antenna: 867,84Mhz -95dB	Spiral antenna: 1301,8Mhz -93dB Pin antenna: 1301,8Mhz -82dB
	Comments: Good module with powerful output.
TX433-5 19x18x7 (w/o pins)	Sp.ant.: 107mA Pin ant.: 119mA	Spiral antenna: 433,9Mhz -51dB Pin antenna: 433,95Mhz -52,5dB	Spiral antenna: N/A Pin antenna: 867,51Mhz -73dB	Spiral antenna: 1301,3Mhz -77dB Pin antenna: 1301,3Mhz -87dB
	Comments: Parameters are like in the TX433-4 module. But it has more current consumption and not good spectrum of harmonics.
TX433-6 11x15x3	65mA	Spiral antenna: 433,95Mhz -52dB Pin antenna: 433,95Mhz -67dB	Spiral antenna: 867,84Mhz -96dB Pin antenna: 867,51Mhz -93dB	Spiral antenna: 1301,92Mhz -96dB Pin antenna: 1301,3Mhz -90dB
	Comments: Described output power was 0,5W, but it’s a fake. Good ordinary module for the spiral antenna, but for pin one it’s not so good.

Summary table for receivers modules:

Number, photo and sizes (in mm)	Current consumption	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
RX315-1 x18x7 (w/o pins)	7mA	Fc=316,5MHz, dF=3,3MHz L>50dB	N/A	N/A
	Comments: High power consumption, but high sensitivity. But the module should be remade, as it comes as 433 MHz.
RX315-2 30x13x4	4mA	Fc=316,0MHz, dF=2,0MHz L>50dB	Fc=438,5MHz, dF=1,0MHz L=20dB	N/A
	Comments: CE pin should be connected to VCC to operate. Module has the very good sensitivity, but it has a parasitic band too. NB: Similar module with “Dl-RXC2015 v.2.0” mark had come defective – it hasn't operated at all.
RX315-3 11,5x17x6	<1mA	Fc=317,0MHz, dF=4,0MHz L=10dB	Fc=340,0MHz, dF=4,0MHz	N/A
	Comments: Very poor sensitivity and selectivity. But supply current is low.
RX315-4 18x8x2	<1mA	Fc=315,0MHz, dF=5,0MHz L>50dB (both with spiral and pin antennas)	N/A	N/A
	Comments: The module has the very good sensitivity and only one band. In addition, it has low supply current too.
RX433-5 12x10x6 (w/o pins)	<1mA	Fc=316,8MHz, dF=1,5MHz L>50dB (both with spiral and pin antennas)	Fc=319,0MHz, dF=1,2MHz L>50dB	+2 bands near 340,0MHz, dF about 1-1,5 MHz
	Comments: It has the very good sensitivity, but poor selectivity – 4 bands in the range from 315 to 340 MHz. SHUT pin should be disconnected.
RX433-1 30x8.5x5 (w/o pins)	<1mA	Fc=434,1MHz, dF=0,7MHz L>50dB	Fc=420,5MHz, dF=1,0MHz	Fc=447,0MHz, dF=1,0MHz
	Comments: Very good sensitivity. But the module has 3 bands.
RX433-2 21,5x9x6	<1mA	Fc=434,8MHz, dF=1,0MHz L=30dB	N/A	N/A
	Comments: It’s one of the best modules in the case of selectivity. But the sensitivity is average.
RX433-3 43x11,5x5 (w/o pins)	<1mA	Fc=432,5MHz, dF=5,0MHz L=25dB	Fc=420,0MHz, dF=1,0MHz	Fc=447,0MHz, dF=1,0MHz
	Comments: One of the worst modules. It has 3 bands. The main band is too wide – 5,0 MHz. The sensitivity is poor. And in addition it’s the biggest module I got.
RX433-4 30x14x8 (w/o pins)	7mA	Fc=435,5MHz, dF=4,3MHz L>50dB	N/A	N/A
	Comments: Module has high sensitivity and only one band. But it has high power consumption – 7 mA as a disadvantage.
RX433-5 18x12x2	<1mA	Fc=435,5MHz, dF=2,0MHz L>50dB	N/A	N/A
	Comments: Module can be unstable and begin to self-oscillate. Similar the 315MHz module (the RX315-4) has more stability.
RX433-6 35x10x8	<1mA	Fc=435,8MHz, dF=0,3MHz L=30dB	N/A	N/A
	Comments: It’s the best module in the case of selectivity. The sensitivity is average, but enough. As a disadvantage, it has relatively big dimensions.

So, I can highlight some modules in the transmitters:

TX315-2 or TX315-3 – Others are worse;
TX433-6 is better with spiral antenna for high-power cases;
TX433-4 is better for pin antenna for high-power cases;
TX433-3 is better for low-power cases.

And in receivers:

RX315-2 if there’s enough power supply;
RX315-4 if the low power consumption is important;
RX433-1 if the high sensitivity is required;
RX433-2 or RX433-6 if the high jam-protection is required.

And in addition, it wasn't obvious for me (I used these modules for the first time) if there’s no useful signal in the air, the output of the receivers has a chaotic signal (it tries to receive any weak signal, and it cause a noise on the output pin as a result). Unpleasantly, the transition to useful signal in most cases could be detected only by a long pause after a packet transmitted. It should be considered if you design your own devices using this types of RF modules.

  The 1st part with methods described.
  The 2nd part with transmitters results.

  The 3rd part with receivers results.

Thursday, October 19, 2017

Comparison of cheap RF modules with ASK modulation. Part 3. Results for receivers.

Disclaimer. Anything in this article is a private opinion guaranteed by Universal Declaration of Human Rights (UDHR). The author doesn’t impose it to anybody. Parameters are shown in this article are relative, and don’t reflect standard parameters of this type of the devices. If one would use different methods of measuring (or different types of measuring devices), the result different. The author doesn’t bear any responsibility for any consequences related to devices described in this article, including a lost profit. Decisions made by a reader are implemented at his own risk. Manufactures who think they are defamed can present their own refutations and the author will publish them with (or without) changing his own opinion.

  The 1st part with methods described.
  The 2nd part with transmitters results.

  The last part with conclusions.

Part 3. Receivers.

Table content:

The 1st band: center F, MHz; Bandwidth, MHz; L, dB - Center frequency in MHz of the main receiving band and it's width in MHz. Maximum level of attenuation of RF-source while receiver can receive useful signal without any noises;
The 2nd band: center F, MHz; Bandwidth, MHz - Center frequency in MHz of the second receiving band and it's width in MHz (if it presents);
The 3rd band: center F, MHz; Bandwidth, MHz - Center frequency in MHz of the third and others receiving bands and their width in MHz (if it presents);

Index number: RX315-1

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
7mA	30x14x8 (w/o pins)	Fc=316,5MHz, dF=3,3MHz L>50dB	N/A	N/A

It was a 433 MHz module. Even if it was described as 315MHz or it was in the set of 315MHz RX/TX modules – it was 433MHz always (see the RX433-4 Module). But I’ve liked this module – it has only 1 band and very good sensitivity. As a disadvantage, it has high power consumption – 7 mA. The receiver is a regenerator, and it has an analog comparator (LM358) on the output.

So, I tried to make it to able to receive 315MHz signals. To do that one should increase both coil’s inductances in 1,37 times. I took the coil from the broken TX315-1 module. So, the “small” coil from that module fits ideally as an antenna one. But the generator coil is not so easy to replace. I cut away the old wire from it (it was primed in the plastic) and I took the wire from the “big” coil from the TX315-1 module and winded it on that “core”. But the required inductance has appeared only when this coil had been primed in the wax.

So, this remake could be completed if you have some equipment to check the receiving frequency.

Index number: RX315-2

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
4mA	30x13x4	Fc=316,0MHz, dF=2,0MHz L>50dB	Fc=438,5MHz, dF=1,0MHz L=20dB	N/A

It's a 315 MHz module. It has a blue PCB with a white mask and mark “WirelessCom DL-RMX2013” on the back side. Chip has no any marks. CE pin should be connected to VCC to operate.

The module has very good sensitivity, but it has a parasitic band too.

By the way – I ordered very similar module with “Dl-RXC2015 v.2.0” mark and it had come defective – it hasn't operated at all.

Index number: RX315-3

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	11,5x17x6	Fc=317,0MHz, dF=4,0MHz L=10dB	Fc=340,0MHz, dF=4,0MHz	N/A

It's a 315MHz module. It has a blue PCB with “LC-technology” mark on the back side. Chip has 480R mark (SYN480R). Very poor sensitivity and selectivity. But the supply current is low.

Index number: RX315-4

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	18x8x2	Fc=315,0MHz, dF=5,0MHz L>50dB (both with spiral and pin antennas)	N/A	N/A

It's a 315MHz module. It has a blue PCB with “H5V3M” mark on the back side. The module has very good sensitivity and only one band. In addition, it has low supply current too.

Index number: RX315-5

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	12x10x6 (w/o pins	Fc=316,8MHz, dF=1,5MHz L>50dB (both with spiral and pin antennas)	Fc=319,0MHz, dF=1,2MHz L>50dB	+2 bands near 340,0MHz, dF about 1-1,5 MHz

It's a 315MHz module. It has a green PCB without any marks. It has a very good sensitivity, but poor selectivity – 4 bands in the range from 315 to 340 MHz. SHUT pin should be disconnected.

Index number: RX433-1

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	30x8,5x5 (w/o pins)	Fc=434,1MHz, dF=0,7MHz L>50dB	Fc=420,5MHz, dF=1,0MHz	Fc=447,0MHz, dF=1,0MHz

It's a 433MHz module. It has a blue PCB without any marks. Chip has no marks too. Only “WL433” mark on the SAW. Very good sensitivity. But there’re 3 bands. Altogether it’s a not bad module.

Index number: RX433-2

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	21,5x9x6	Fc=434,8MHz, dF=1,0MHz L=30dB	N/A	N/A

It's a 433MHz module. But seller described it as a 315 MHz. It has a blue PCB with “LR45B” mark on the back side. Chip has no marks. I think it’s one of the best modules in the case of selectivity. But sensitivity is average, many other modules have better one. But if one cares about jam-protection - it’s the best choice.

Index number: RX433-3

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	43x11,5x5 (w/o pins)	Fc=432,5MHz, dF=5,0MHz L=25dB	Fc=420,0MHz, dF=1,0MHz	Fc=447,0MHz, dF=1,0MHz

It's a 433MHz module. It has a green PCB with “RXB6 2.0” mark on the back side. Don’t be fooled by this cute metal cover – it’s one of the worst modules. Chip is SYN500R. There’re 3 bands. The main band is too wide – 5,0 MHz. Sensitivity is poor. And in addition, it’s the biggest module I got.

Index number: RX433-4

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
7mA	30x14x8 (w/o pins)	Fc=435,5MHz, dF=4,3MHz L>50dB	N/A	N/A

It's a 433MHz module. It has a green PCB with “MX-RM-5V” mark on the back side. It has no synthesizer, the receiver is a regenerator. This module could be remade to 315MHz (see the RX315-1). It has a high sensitivity and only one band. But it has a high power consumption – 7 mA as a disadvantage.

Index number: RX433-5

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	18x12x2	Fc=435,5MHz, dF=2,0MHz L>50dB	N/A	N/A

It's a 433MHz module. It has a blue PCB with “H5V4D” mark on the back side. Attention! The module can be unstable and begin to self-oscillate. Similar the 315MHz module (the RX315-4) has more stability.

Index number: RX433-6

Current consumption	Dimensions, mm	1st band, center F, MHz Bandwidth, MHz L, dB (more is better)	2nd band, center F, MHz Bandwidth, MHz	3rd band, center F, MHz Bandwidth, MHz
<1mA	35x10x8	Fc=435,8MHz, dF=0,3MHz L=30dB	N/A	N/A

It's a 433MHz module. It has a blue PCB with “SRX882 V1.1” mark on the back side. It is the only superheterodyne from all modules I got. Chip is PT4303-S. CS pin should be connected to VCC to operate. This module brought me to a doubt. It must have 433,9MHz as center frequency by calculations, but it has almost 436MHz. But it received signals from the 433MHz wireless doorbell very well. Maybe my method of measuring is wrong, but with the other modules, this method showed believable results. Anyway, it’s the best module in case of selectivity. The sensitivity is average, but enough. As a disadvantage, it has relatively big dimensions.